Tracking QB Rating over time

Posted on November 16, 2013 by Brent

Limited commentary with this post, because it’s somewhat self-explanatory. I decided to go back and calculate an on-going QB Rating for several prominent players to see how each would have looked, statistically, after every appearance made. Obviously, this relates to Nick Foles. Basically, I cannot think of a single QB who has had a start to his career anywhere near as good as Foles has (statistically) and then NOT gone on to have a good career. However, I figured it would be instructive to look at some successful QBs and see how they progressed over time. Below is the chart.

Before we get there, though, a PSA: The NFL QB Rating calculation, while useful, is very convoluted. Almost nobody knows it or has even seen it, so for your education, here it is (from Wikipedia):

Fun stuff, eh?

Anyway, back to the subject. Here’s the graph, I suggest you click to enlarge:

I only included the first 100 appearances (NOT starts) for each player. Note that this is an ongoing calculation, so it becomes less susceptible to change with every appearance. I’m hesitant to draw any conclusions from such a small sample size, but including other QBs (I originally included Vick, Brady, Brees, and Josh Freeman) makes the graph too hard to read.

In any case, I’m going to build the sample from here to see if we can divine a good idea of when, regarding Foles, we can exhale. For now, just take note of how “poorly” each of the included QBs played to start their careers. And because you knew I would, I included Foles below, along with Brady and Brees. Notice that none of these guys had as high a QB rating after 14 appearances as Foles does. Moreover, among these guys, Foles tracks most closely with…Tom Brady. I know attempts would be a more helpful measure, but I don’t have data for that, so…this:

Update: Should have noted this originally, but the chart doesn’t account for the general offensive inflation the league has seen since guys like Peyton started their careers. Regardless, the adjustment would only involve shifting Foles’ line down slightly, and would’t significantly change how things look. The trend, obviously, would remain the same.

How often do good QBs have bad games?

Posted on November 12, 2013 by Brent

Another game, another great statistical performance from Nick Foles. This one was certainly luckier than some of his previous gems, but that’s hardly a good reason for writing it off completely. While thinking through his performance, I decided to look at the topic referenced in the title to this post. Before that, some quick notes on Foles:

– With each game, Foles’ sample size grows, and the odds of him being a “fluke” decline. As promised, here’s his updated QB Rating by game chart:

– Eagles fans might not fully appreciate this, but having a QB whose “bad” games don’t involve a lot of turnovers is not a bad place to be. McNabb never turned the ball over, but perhaps Vick has given you some perspective. Most “bad” QB games are a lot uglier than we’ve seen from Foles.

– Going back to our strategic equation (E = R ((60 – T) / 60) + C), and applying it to yesterday’s game, we can see that Foles’ relatively underwhelming performance might have been the result of very rational decision-making. When Seneca Wallace left the game, leaving Scott Tolzien to lead the Packers, the Relative Strength swung largely towards the Eagles. As a result, they became the strong favorite, meaning they should be playing a LOW-variance game. For Foles, this meant avoiding turnovers at all costs. I don’t know whether this was actually the case or not (probably not), but Foles would have been completely justified in not throwing to WRs unless they were VERY open. After grabbing a lead, it became somewhat clear that the best chance for the Packers to win lay in the Eagles turning the ball over. If Foles/Kelly made a conscious decision to go with low-risk plays, then the result would look underwhelming but, in fact, be the right strategic call.

– Of course, Foles DID throw one ball into coverage, but it was on a deep throw. While I have not confirmed on the replay, my initial take on the play was somewhat different from most others. In my view, he did NOT throw “into double-coverage”. He under-threw D-Jax, the result of which gave a second defender time to get into the play. That seems like a slight difference, but it’s important. There are two aspects to the play:

1) the decision to throw the ball (mental)

2) the actual throw (physical)

I think Foles got the first half 100% correct, he just messed up the execution. In general, a slightly under thrown deep-ball is a lot more defensible than a decision to throw into actual double-coverage.

Ok, enough about Foles. In thinking through the odds/fluke/sample-size piece, I decided it would be interesting to provide some context to the QB expectations discussion. I did a little of this when I talked about McNabb’s HOF credentials, but today I’ll do it in more detail.

The overall point is that most fans (I think), overrate the consistency of “great” QBs and set their expectations for the position too high. Great QBs have bad games, and as we’ll see (I hope), they happen more often than you’d think.

Setting it up

First we need to define our parameters. I’m going to use QB Rating, with all relevant caveats acknowledged. For our categories, I’m using the following:

Great: 105+

Good: 95-104

Decent: 85-94

Poor: 75-84

Bad: < 75

Below are charts for a selection of QBs. I only included starts with at least 10 pass attempts. Sorry for the blurriness, click for a clearer picture.

Take a good look, cause there’s a lot of good information in there. Most important, of course, is the frequency of “bad” games (rating of worse than 75).

– Tom Brady has a “bad” game roughly 25% of the time.

– Drew Brees has a “bad” game nearly 1/3 of the time.

– Even Peyton Manning doesn’t crack a rating of 75 in almost 20% of his starts.

That doesn’t even include the incidence of “poor” games either. When you add that in, you can start to see the point I’m trying to make. Even the best QBs in the league have what fans would consider a bad game fairly often. Now they do, obviously, provide a high rate of “great” games as well, that’s what makes them “great quarterbacks”.

A couple more notes:

– Tony Romo compares favorably too both Drew Brees and Tom Brady (commence vomiting now)

– FutureHallOfFamer Eli Manning’s starts have resulted in either “bad” or “poor” performances more than half the time (54%). Let that sink in….if you randomly picked a game from Eli’s career, you’re more likely to get a poor/bad game than a decent/good/great game. It’s not too late to kill his HOF candidacy…

So next time Nick Foles has a bad game (like that’s every going to happen again), remember this post. Even the greatest QBs have bad games, and it happens more often than you’d think.

Eagles vs. Packers: Breaking Down the Odds

Posted on November 9, 2013 by Brent

Below is a repost of the weekly odds column I do at BGN

Nailed it last week, though I wasn’t very confident in my Over pick. Starting to see a trend here; when the Eagles get competent QB play, they hit the over. Whether they’ll get decent play from the QB each week is a tough prediction to make though.

This week, we’ve got some issues breaking down the line. Prior to the Rodgers injury, the Packers were favored by 10 points. Now they’re favored by just 1.

From a pure handicapping perspective, this would have been a lot easier with Rodgers healthy. Of course, we all want the Eagles to win, and playing against Seneca Wallace instead is a huge break.

So…the lines

Eagles +1

The Spread

As you can imagine, getting 1 point isn’t a huge advantage, so we’re basically trying to figure out which team is more likely to win. If it’s 50/50, then you take the point. Anything else, and you take the team more likely to win. First, lets consult Football Outsiders.

– The Packers rank 10th overall by DVOA, the Eagles rank 16th.

– The Packers offense is the team’s biggest strength, coming in 2nd by DVOA (23.5%). The Eagles are relatively close behind, ranking 6th overall on offense (14.8%).

– The Packers rank 26th by DVOA on defense (7.1%), while the Eagles rank 30th (13.4%)

– The teams have nearly identical special teams rankings, coming in 25th (GB) and 26th (PHI), with a DVOA difference of just 0.9%.

Without the injury to Rodgers, it’s a clear advantage for GB. However, I think 10 points was a bit excessive, and frankly might have rather taken the Eagles in that situation getting 10 points instead of taking them now against Wallace with just 1 point. But it is what it is, so lets work with what we’ve got. First question:

Will Nick Foles provide decent or better QB play? If so, then the Eagles will score plenty. The Packers defense, as illustrated above, isn’t good. I should also note that, in the FO DVOA rankings, Green Bay is just one spot above Oakland. So while we shouldn’t expect 7 TDs again, it’s completely reasonable to expect a good performance, and something on the order of 30 points. In the games in which the Eagles QB has played reasonably well, the Eagles have scored 33, 30, 36, 31, and 49 points. Going against a bad defense, I’m comfortable with setting a 28-35 point expectation from the Eagles. Unfortunately, if bad Foles shows up, they may not hit 10 points. I’m assuming we’ll see decent-not-spectacular Foles.

How should we view Seneca Wallace? Seneca Wallace is NOT a complete unknown. The guy has been in the league since 2005 and has played in parts of 64 games, starting 21 of them. In that time, he has a Rating of 80.6, a completion percentage of 59.1%, an interception rate of 2.4%, and a sack rate of 7%.

Overall, that amounts to a slightly below average QB.

Replacing Rodgers, who is, at this point, putting up the greatest statistical career ever for a QB with a slightly below average QB is a massive difference. But how much?

Well if we expect a performance in line with his career averages, we’re essentially looking at this years’ Alex Smith, with a slightly higher propensity for interceptions. Against Smith, the Eagles allowed 26 points. However, 7 points came from Eric Berry’s pick-six. Now the rest of the Packers offense is better than the Chiefs, but not by that much. The difference really is mostly Rodgers. The Packers receivers look to present a bigger challenge than the Chiefs did, so we should adjust upwards there, since the Eagles weakness has been through the air. How much is Nelson/Cobb instead of Bowe/Avery worth? A few points? Lets be extra conservative and call it 7. So we’re looking at a rough range of 24-30 points. (I’m writing off Lacy-Charles as a wash, not because that’s fair, but because it makes our estimate even more conservative and gives us a greater margin of confidence).

Since I had the Eagles at a range of 28-35 points, that means take the Eagles +1. Just know that the high-variance nature of Foles’ play means it’s a relatively binary outcome. If Foles can deliver the ball with some accuracy, I like the Eagles. I think it’s more likely than not that we see an at-least-decent Foles. Therefore, take the point.

The Over/Under

The line is 47. Taking the mid-point of the ranges I set above gives us around 58 points. That’s a big difference. Usually, when the difference is that big, it means either we did something wrong or one of our assumptions is way off. If it’s neither, than we need a good explanation of why “the market” is off. What’s my story?

– Overreaction to Wallace’s poor showing in relief (11 of 19 with an interception). Wallace will likely be better than the general public expects. Remember we have a pretty good sample on him (783 career attempts).

– Still underestimating Nick Foles. If I wasn’t from Philadelphia and I wasn’t paying as close attention as I have been, I’d likely dismiss Foles as well. He just doesn’t have the pedigree. Of course, the people paying close attention know the truth; Foles has been a pretty damn good QB so far. He had a terrible performance against Dallas, and I think people are likely still giving that significant weight. In fact, I think his record-tying performance last week might actually work AGAINST him. It was so cartoonish that it’s easy to dismiss as a fluke. “Nick Foles playing the best game ever by a QB? C’mon. He just got lucky.” Conversely, if he had played really well, but only thrown 4 TDs, I think the story would be harder to write off. It doesn’t make any logical sense, but remember we’re dealing with people, logic doesn’t always apply.

Also, Eagles games this year have failed to hit 47 points just 3 times. Once was against the Chiefs (great defense) and the other two were the Barkley game and the bad-Foles game. Every other game has hit at least 51 points.

Also, the Eagles are 5-0 against the O/U on the road this season. I don’t actually put much weight into this fact, but it’s a nice confidence boost.

Conclusion

I like the Over 47 most.

I like the Eagles +1

It all hinges on Nick Foles. That sounds obvious, and it is, but the key nuance is that Nick Foles doesn’t need to be great, or even very good. If he just does what a decent QB should do (hit open men and not make stupid mistakes/TOs), that should be enough. I think the odds favor him reaching that level of play.

You can follow me @EaglesRewind

Notes on Nick Foles

Posted on November 7, 2013 by Brent

Been swamped the past few days, hence the lateness of this post. I originally intended to just post my normal post-game notes, but I think at this point everyone has already read enough about that game. It was awesome, encouraging, etc.., but it was also against the Raiders, so let’s try to contain ourselves just a bit.

I do, though, want to talk more about Nick Foles (of course). A few points:

– First, I promised to update this chart (Foles’ rating by game), so here it is:

You can come to your own conclusions. Remember, I only included games in which Foles threw at least 10 passes.

– Nick Foles DID play last year. In some of the write-ups about him that I’ve seen, its as though the kid’s first action came this season. It didn’t. He played in 7 games last year and had 265 pass attempts. He finished with a QB Rating of 79.1, which as I’ve showed, is VERY good for a rookie. He did benefit from some dropped interceptions, so have to discount the rating, but he ALSO played behind a bad O-Line and, at times, didn’t have his best “weapons”.

So it’s not as if his performance over the past few weeks came out of nowhere (both good and bad). Over the entire offseason, I tried to emphasize that Foles’ performance as a rookie was strong, and while he wasn’t (and still isn’t) the definite “answer”, his play certainly should have earned him a chance to start.

– What exactly are Foles’ strengths and weaknesses? Coming into this year, I thought we had Foles pegged. He showed good pocket awareness and was very accurate on the short-intermediate throws. The big question marks involved his arm strength. He struggled a bit on sideline throws and while he was able to get the ball downfield, his accuracy on those throws was poor.

Well….the past two starts for Foles have completely undercut those assumptions. Against Dallas, his short-throw accuracy was terrible and his awareness was severely lacking. Conversely, against the Raiders, he clearly demonstrated an ability to not only push the ball downfield on deep throws, but to do so with good accuracy. I mentioned at the end of last year and over the offseason that the deep-throw accuracy was something he SHOULD be able to improve upon, whether through better technique or actual strength-training. It’s possible what we saw against the Raiders was an outgrowth of that type of improvement.

Overall, we essentially have to completely rebuild our assumptions about him. Barring another Cowboys-like performance, I’d be surprised if Foles didn’t start the rest of the way, so we should get plenty of chances to refine our expectations, but for now we’re back to square one. Theoretically, he CAN do everything (except run fast). But we need to know which parts of his game are consistent enough to be called “strengths” and which ones are inconsistent enough to be called “weaknesses”.

– How does he stack up when compared to other notable QBs? I wanted to do a full post on this, but it looks like ChipWagon beat me to it, at least partially. However, let me take an abbreviated crack at it. Here is Nick Foles, in comparison to notable quarterbacks over similar Pass Attempt samples to start their careers. Note, this is by no means a representative sample. I picked QBs who are both successful and had a similar number of attempts their first year in the league (so I didn’t have to calculate). Big note here is that Foles’ numbers are over parts of the first 2 seasons, whereas the rest came from 1 season (I did include the 3 attempts Brady had his rookie season).

So…yeah, pretty good. The interception rate in particular is phenomenal. Remember that Foles benefited from a relatively high number of dropped INTs last year. However, this year I don’t recall seeing many, though I haven’t seen the actual count from Football Outsiders (I don’t think it’s available until year-end, if I’m wrong about this please tell me). Also, despite Foles famous lack of speed, his sack rate is either better or comparable to every player in that table other than Matt Ryan. To beat a dead horse, POCKET mobility and awareness is much more important that straight line speed or rushing ability.

The biggest caveat, of course, is that we’re looking at these numbers after perhaps the greatest statistical performance by a QB in the history of the NFL. That’s a bad time to do it, but I didn’t want to wait. To rectify, I’ll update Foles’ numbers after this week and maybe each week from here on so we can get a continuing look at how he stacks up.

Eagles vs. Raiders: Pre-Game Notes

Posted on November 3, 2013 by Brent

We’re entering the second half of the Eagles schedule, and I think it’s safe to say that while some questions have been answered (Chip’s offense works, Barkley fell for a reason, Cole/Graham are not the answer at OLB, etc…) many more persist. Unfortunately, the Eagles look like they’re too good to secure a top draft pick and too bad to really threaten anyone in the playoffs. still plenty of time for that to change, but for now, it’s best to focus on the questions we CAN answer, or should be able to. For today, mine look like this:

– What’s Nick Foles’ ceiling? Let’s start with the obvious one. He’s either a starting caliber QB with good accuracy and the ability to consistently pilot the team on scoring drives, a solid backup who can step in for short stretches and avoid turnovers, or completely overmatched (see Dallas game). We’re not going to answer that definitively today, but every start Foles gets is another piece of evidence with which to judge his potential. I don’t think he’s Chip Kelly’s “guy”, but if he plays well he may have some trade value or at least provide a viable enough option that Chip can take his time to find “his guy” instead of reaching for one in next year’s draft.

– What’s Bennie Logan’s deal? I didn’t like this pick when the Eagles made it, but that was more value-based than commentary on Logan’s potential. With Sopoaga gone, Logan knows the job is his if he can handle it. He’s still a bit undersized, so he might deserve some leeway until he fully adjusts; but make no mistake, the clock’s ticking. I don’t know how Davis or Kelly feel about the NT position, but in my opinion, it’s an area where you can’t settle for just adequate. So keep an eye on Logan and see how often he “flashes” above-average potential.

– Is the defensive improvement an aberration, or has Davis figured a few things out? A lot of people are claiming the Eagles have turned a corner of defense…I’m not so sure. They’ve benefited from facing some very bad offenses recently (Giants twice, Bucs). Of course, you can only beat who you play, so we can’t write the performances off entirely, but it’s something to keep an mind. Unfortunately (for an answer, not for the Eagles), Oakland isn’t a very good offense either. They’ve looked a bit more dangerous with Pryor under center, but they still rank 28th overall in DVOA (Football Outsiders). In particular, the Raiders’ passing game has struggled (30th by DVOA). So, if the Eagles really have improved on defense, they should have another strong game today. However, even if they do, we should probably still be skeptical.

– What is Chip Kelly’s strategic philosophy? I thought he’d be more “aggressive”, making higher-risk calls when the associated return warranted it (think optimizing expected points). I also thought he’d be more aggressive on 4th downs. That hasn’t really panned out, but we don’t know exactly why. My guess is that if he had “his guy” at QB, we’d see a lot more of that stuff. This team’s got a lot of weaknesses, and it’s possible Chip just doesn’t trust it enough to execute. Or, I and many others just misread Kelly and he’ll be much more conventional when it comes to strategic decisions than I’d hoped. This question, in particular, will not be answerable for quite some time. However, it’s arguably the most important one I’ve posed here, so we’ve got to look for hints of an answer every game.

I’ll leave it there for now. As far as the game goes, I think it’s simple, if Foles can split the difference between his performances against the Bucs and Cowboys, the Eagles win. If he’s worse, they lose, barring a corresponding bad game from Pryor. Meanwhile, the Cowboys play the Vikings, so a loss today for the Eagles will probably leave them 2 games out of the division race.

Nick Foles: Information assimilation

Posted on November 1, 2013 by Brent

I was hoping to make this post about the equation I drew up earlier, particularly how to think about assimilating new information into the model. Given this week’s Eagles scenario, though, I think it’ll be helpful to apply similar thinking to a real world example first, then go back to the model.

The “real world” example is, of course, Nick Foles.

His last start was terrible. He looked completely overmatched and showed none of the strengths we had previously seen him use (pocket presence and accuracy in particular). That’s not really up for debate. However, there’s a BIG difference between knowing that information and using that information. The issue is, what does this performance tell us about Nick Foles’ skill/ability in general?

To answer that with any confidence, we have to frame it correctly. That means using ALL of our information, not just last game. For example, here’s a chart that shows Nick Foles’ passer rating by game. I’ve only included games in which he had at least 10 pass attempts.

What do we see?

– Well most shocking to me is that the Cowboys game wasn’t actually Foles’ worst game (by passer rating).

– The sample size (look at the X-axis labels) is still very small. He’s only seen significant time in 10 games. That means, regardless of what you think his performance to date says, you shouldn’t have that much confidence in it.

– When put in context, last week looks like an extreme outlier. This is why it’s important to view everything together, rather than focus on one particular event.

Insert Passer Rating disclaimer here.

So we’ve got a general idea of the larger picture. Now let’s take a sightly different approach. First, let’s use what we KNEW about Foles BEFORE the Cowboys game to see just how likely the Cowboys result was. Caution: Extremely over-simplified statistical analysis here. It’s illustrative, not definitive. There are definitely some more robust tools we can apply and some data adjustments we can make to increase confidence, but that’s a post for another day. Apologies in advance to the statisticians out there.

Prior to that game, Foles career Passer Rating was 87.13. Let’s assume, for a moment, that 87.13 is Foles’ “true” ability. It probably isn’t (small sample), but IF IT IS, we want to know how likely the Cowboys game result was. To do that, we’ll need not just his rating, but the standard deviation as well, which for Foles, was 27.03.

Given those to pieces of information, and assuming a Normal distribution (not necessarily a safe assumption) of potential outcomes, we can calculate what the odds were of Foles performing that badly. Now, this doesn’t account for defensive strength, but I’m trying to keep things relatively simple.

In a Normal distribution, roughly 68% of the data will fall within one standard deviation of the mean.

Here, the mean is 87.13, so we would expect, if that’s Foles “true” ability, that 68% of his starts would result in a Passer Rating between 60 and 114 (rounded).

Now, Foles ended the Cowboys game with a Rating of 46.2, which is roughly 1.5 standard deviations (27.03) away from the mean (87.13). 1.5 is the Z-Score.

Cutting to the chase, that tells us that, given our assumptions, the odds of Foles performing that poorly against the Cowboys was just 6.5%.

We can’t stop there, of course. Just getting the result isn’t enough. We then have to go back and view the observed outcome in light of its probability and our assumptions. Basically, there are two ways of viewing this:

– Foles performance was a result of random chance. Given what we knew, he had a 6.5% chance of playing that poorly, and it just happened to hit.

– Our initial assumption was wrong. Foles’ “true” Rating is worse than 87, which means the likelihood of him playing that poorly was actually higher (potentially much higher) than 6.5%. This one is attractive, because it let’s us increase the odds of occurrence for the event we witnessed.

I’m not yet ready to answer that question, but this is the real crux of the post, and the overall point I am trying to make. If you actually want to KNOW what’s going on, you have to examine all of the information, and try to reconcile it. Most fans, of course, have no interest in doing this. They’ll trust their “gut”, which usually results in them using the most recent event and discarding almost everything else. Think about the euphoria after the Bucs game. If you go back to the chart at the top of the post, it’s clear that was an outlier as well, though it was part of the overall uptrend and not as serious as the Cowboys game.

A big part of objective analysis is accepting that there’s usually a real chance that you’re wrong. In this example, we can view this from both sides. Foles supporters, while pointing to the “bad luck” explanation, HAVE to accept that fact that the second explanation, “bad Foles”, may be true. Similarly, Foles detractors can point to the “bad Foles” explanation and use the Cowboys game as proof that the Foles supporter were wrong. However, they too must recognize the potential validity of the alternative explanation. It’s possible (6.5% in our basic analysis), that it was simply a bad game.

Reconciling those two sides is mandatory for anyone try to learn the truth. As I tried to explain in the short disclaimer above, the example I used was extremely simplistic. It doesn’t account for things like quality of competition, potential for improvement, etc. There’s also the Normal distribution assumption and the small sample issue. There are things we can do to address a lot of those problems, I just didn’t have time to do it all for today’s post.

Going back to the larger topic of Information Assimilation, hopefully you can see how this type of analysis can be applied to the R value in our equation. And for anyone still skeptical as to the applicability of that model, I give you this:

Look at the score by quarter and tell me E = R ((60 – T) / 60) + C isn’t important.

Momentum: Yes it’s real…but that’s no excuse

Posted on October 30, 2013 by Brent

Before I get to today’s topic, Momentum, I wanted to note that yesterday’s post, The Hot Seat Index, has now been updated. There was a flaw in the win change column of the table that was helpfully pointed out by a commenter. It’s now fixed. The results aren’t dramatically different, but scroll down to see the update if you want.

Now…

Everybody who watches the NFL (or any sport for that matter) is familiar with the term “momentum”. It’s used very often by commentators and announcers to describe the ebb and flow of the game. More importantly, it’s dismissed and derided by the “analytic” community. On the surface, it’s a clear front in the battle between “old school” and “new school” fans/analysts/etc… Now I want to weigh in.

As you may have predicted, at a high level, I agree with the “new school”. However, I think a lot of the members of the side of the discussion, whether through inattention or ignorance, aren’t characterizing Momentum correctly.

Momentum absolutely exists.

I have no doubts about that. So why do I still agree with the analytic community over momentum’s relative worthlessness?

Well first, let me define momentum exactly as I see it. When we discuss Momentum, we’re essentially saying that the events of the game have unfolded such that a player’s expected performance distribution fundamentally changes. Some combination of pressure, confidence, attitude, etc…, supposedly diminishes the expected performance of the players.

I’m willing to admit that it’s possible for a player to underperform his true ability based on one or more of these factors. However, why is the converse not possible? Given a host of different stimuli, we can find people who react to said stimuli in contrary ways. Just as not “having the momentum” can diminish performance in some players, it seems logical that it can also INCREASE performance among other players. For example, can you think of any athletes that seem to play BETTER when they are losing by a lot or when the other team seems to “have” the momentum? If so, we have a problem. In order to assert Momentum, you’d have to accurately balance the players who play worse against those who play better.

More importantly, in football, there are a LOT of players on the field at once. Even if we knew how one player would react, it wouldn’t tell us much about the game unless we knew how the OTHER 21 players on the field reacted.

That’s a long way of saying that, even if Momentum is real, it is NOT knowable. We can’t even agree on what factors play a role, let alone measure them. If a factor is not measurable, or even theoretically knowable, is it of any actual value?

Let’s equate it to Luck. Clearly, luck is real and plays a very real role in the outcome of NFL games. However, luck, as I’m thinking of it, is also UNKNOWABLE. We don’t know how the ball will bounce once it’s fumbled. We don’t know if a sudden wind gust will blow a field goal off course. So we have a similar knowledge of luck and momentum.

However, commentators appear to think we KNOW things about momentum that we can’t possible know. Let’s play a game. I’m going to list a common phrase, then we’ll do a little variable replacement.

– “Team A really needs to score to shift the momentum”

Hear it all the time. As we’ve just discussed, we have just as much knowledge about momentum as we do about luck, so what happens when we use that equivalence to rewrite the sentence above?

– “Team A really needs to score to shift the luck”

Sounds ridiculous, right? Like, completely outrageous and anyone who said it on the air would be ridiculed mercilessly.

So why are we so tolerant when commentators use “momentum”? As I tried to explain, we don’t really know anymore about the effects, conditional requirements, or significance of momentum, so isn’t it ridiculous to assert it as a goal?

Or how about:

– “Team B really has the momentum on their side now!”

We have no idea what that means! We CAN’T know what that means, because momentum is made up of an extremely large number of unquantifiable variables, the effects of which are unclear even if we DID know how to measure them. It’s as ridiculous as saying:

– “Team B really has the luck on their side now!”

It doesn’t make any sense, and it’s worthless as an explanatory phrase.

Now, this doesn’t mean that “momentum” should be stricken from the vocabulary of every announcer. Just as there are very appropriate uses of “luck” while describing the game, there are potentially valid uses of “momentum”.

The problem occurs when announcers and fans start using MOMENTUM as a justification for play-calling or as a goal itself. For example, going for it on fourth down because you “had” the momentum. It’s likely that going for it was the right move (see previous posts), but that justification is ridiculous. There’s just absolutely no way of knowing if the particular circumstances at any point in time qualify as “Momentum” or if that actually means that your players are more likely to perform or the other team is any less likely to perform.

I don’t think most announcers think about these things when they use the phrase. It’s, unfortunately, a descriptive crutch. It’s just another way of saying “Team A has made a lot of good plays in close succession”. That in itself isn’t a huge offense, but it’s frequently used to justify some assertion that Team A is then MORE LIKELY to be successful on plays until the momentum changes again.

That of course is ridiculous, and why most “analytic” minded fans and commentators are so dismissive of the concept in general. If it ended at a description of what HAS happened rather than support for what WILL happen, it would’t be nearly as annoying.

So…the final point:

Momentum is very real. However, it’s not quantifiable or knowable, and therefore is completely useless to us in terms of advancing our understanding of the NFL or sports in general.

Now…about “clutch”…

The Hot Seat Index: Predicting NFL Coaching Terminations

Posted on October 29, 2013 by Brent

Time for another guest post from Jared. You may remember him from:

– One of the Coolest NFL Charts Ever

– The Fourth Down Decision Series and Cheat Sheet (Part 1 of 4)

– When does it make sense to return a kick?

Well today, he’s ready to unveil at least the first iteration of his Hot Seat Index, and attempt to predict which coaches will be fired at or by the end of the season. You can follow him @jaredscohen and at kebertxela.blogspot.com. Without further ado:

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So the Eagles had another especially depressing loss to the Giants this week. And with such a depressing loss, it got me thinking of another depressing outcome, watching your team stink to the point where they fire their coach.

So, this was something I wanted to wait on until much later in the season, but with Greg Schiano working as hard as he can to get fired as soon as possible, I needed to put it out a bit early.

One of the things I hate hearing about as the NFL season progresses is all the discussion around the coaching ‘hot seat’. It’s not that I mind the speculation, but all of the discussion centers on conjecture and the occasional ‘anonymous source’ (the exception being Schiano where the sources have noticeably opted to forgo anonymity!)

As I was thinking about it, I really wanted to see if we could make this a bit more objective and data driven. So with that as the goal, I gathered some data, did some analysis, and am now ready to introduce the NFL Coaching Hot Seat Index!

The Coaching Hot Seat Index is a model that, at any point in the season, will give you the approximate odds of an NFL coach getting fired after the season!

It’s based on a collection of data on all NFL coaching seasons since 1980. I broke the data down and for each coaching season, identified whether a coach was fired or kept their job (with some adjustments for retirements etc.)

With over 900 observations (and ~200 firings!), I started looking for factors which were significant in predicting whether coaches got fired or not. I tried lots of things, number of wins, playoff appearances, having the last name ‘Kotite”, all to see what was really significant in predicting when a coach will get fired.

I ended up with two primary factors, which were by far the most significant in predicting a coach getting kicked to the curb.

– Total point differential (points scored-points given up)
– Change in team wins from prior season (current year wins-prior year wins)

Those shouldn’t come as a huge surprise. (Note: I’m disappointed because I couldn’t examine another factor I wanted to see, the difference between Expected Wins at the Season Start and Actual Wins at season’s end…I wanted to use gambling lines to get at it but didn’t have nearly enough data to look at it. I still think it would be a more compelling variable)

But anyway, with those two factors, and using (or, abusing) a technique called logistic regression, I arrived at an equation to give us the odds a coach will get fired. Logistic regression is basically something you can use to help predict the likelihood of a binary outcome (a coach either gets fired, or he doesn’t) based on some variables (in this case, his team’s point differential and win change from prior season).

In the end, the result is the percentage chance (out of 100%) a coach will be fired after the season. The higher the odds, the more likely the coach is going to be filing some unemployment papers right around the Pro Bowl.

But I couldn’t just create a model and throw it out there without testing it a little. So I created a first draft of it, using only data from 1980-2011, and used that model to ‘predict’ the 2012 season based on its point differential and change in team wins (which, obviously, I already knew). When that passed the sanity check, I updated the model for 2012 and used it on teams from this year.

Those results are included below, with coaches sorted by their ‘odds to be fired’

Not a bad first result. Romeo Crennel, Mike Mularkey, Andy Reid all got canned, and those were the coaches with the highest likelihood. The model obviously isn’t perfect, as the plenty of coaches can still get fired, but at least there’s a structure and some logic here (we can also rank the coaches from safest to least safe!!!)

So this is interesting, and now we can apply it to the current season, and see what 2013 coaches are most likely to be fired!!!

Now, I had to make a couple of assumptions, because this model is based on a full season of performance, which of course we won’t have. But we do have a good sample and some reasonable projections of performance we can use as proxies.

For point differential, we can use a teams’ current point differential and pro rate it out for 16 games. This doesn’t account for changes in either a team’s performance or strength of schedule, but it’s not unreasonable.

For win difference from last year, we can take an estimate of the team’s full season (which I’ve borrowed from Football Outsiders Playoff Odds report, which runs simulations to calculate average team wins) and then just check the difference from 2012 wins.

So, at this point in the season (Week 7, because Week 8 is going on as I write this), which coaches have the highest odds of getting fired?

Well – it’s no surprise to see the Jaguars on the list, but we may have to make an exception for first year coaches as they typically get more than one season to right the ship. We’ll give Gus Bradley a pass (although no one can argue their performance is historically bad…it’s no wonder the odds are higher than anything seen in 2012)

Tom Coughlin checks in at number 2, ~~although we’ll unfortunately need to update that after the Eagles managed to lose to them this week.~~ Their performance has been really bad as well, and any coach without Super Bowl rings would likely be on their way out. But Coughlin may overcome the odds with all the goodwill he’s built over the years (or maybe he changes his mind and “retires”)

Next comes Schiano, where I think we can all agree the odds calculation actually UNDERRATES his odds of being let go. This guy might want to think about booking some tee times in late November if he continues at his current pace.

But the next coaches on the hot seat, Gary Kubiak, Leslie Frazier, and Mike Shanahan, should also probably get their acts together if they want to stay employed.

From an Eagles perspective, Chip Kelly doesn’t seem to be in too much danger (although as I said, we probably should eliminate all first year coaches as a general rule). Of course, this assumes Kelly behaves competently, unlike the absolute sh*t show we just saw against the Giants (which my brother is probably already dissecting)

Of course, from a FORMER Eagles perspective, it looks like Andy Reid has done quite alright for himself in the move to Kansas City.

I’m just saying.

Eagles vs. Giants: Week 8 Post-Game Thoughts

Posted on October 28, 2013 by Brent

Backlog of posts for this week, including another guest post from Jared, who did the 4th down decision series, a note about “momentum”, and more on expected points and underdog strategy. First, though, I have to say a few things about yesterday’s game.

– If you’re forced into playing a 4th round rookie at QB, all bets are off. To that end, don’t read too much into the performance. The defense was OK (not as good as some have claimed, but not a disaster) and there were plenty of opportunities for the offense to move, Barkley just couldn’t get it done. That marks the second week in a row that the Eagles lost a game that they would have likely won with just average QB play. If they get that, we’re looking at 5-3, 1st place in the division, and a whole different storyline.

– Keep the defensive performance in context. The defense looked competent, and many are running with the “they’ve turned a corner” storyline, but I think it’s too early for that. Consider: The Giants are a TERRIBLE offense. Additionally, while the Eagles kept the Giants out of the end one, they also allowed the Giants to score points on 5 of the first 6 drives, and forced just one three-and-out in the first half (the 1st possession). The also sacked Eli Manning just once (he had been sacked 18 times in the first 7 games of the season, or roughly 2.5 per game). So yes, the point total against was a good result (15), but in context, it was just an OK performance.

– Vinny Curry was back on the bench. This is just one of Kelly’s (and Davis’) many perplexing decisions during the game. As I said pre-game, this was a great opportunity to play Curry without worrying about his problems against the run. Instead, he got just 12 snaps (and the Eagles struggled to get a pass rush). I have no particular insight here, other than saying that logic is clearly not the determining factor in the playing time decisions.

– Matt Barkley isn’t the guy. I’m usually the first person to urge caution and restraint when making snap judgments based on small sample sizes. However, there were two plays Barkley “made” that I found extremely troubling. I’m sure everyone knows which ones I’m talking about (the fumble and the 4th and 20 check down). Normally, we could pass these things off as “rookie mistakes”. Unfortunately, it seems like Matt Barkley’s biggest strength should be “Football IQ”. He’s been starting for big-time programs forever. Nothing about either of these situations is materially different in the pros. Maybe I’m being to harsh on him (as I said, most rookies would deserve a pass), but he’s a unique player by virtue of his experience.

– Are the Eagles stuck in no man’s land? I probably should have listed this first, because it’s arguably the most important point, but I’ll leave it here as a reward for reading this far. Here’s the dilemma:

1) The Eagles clearly do not have the talent to seriously contend for a Super Bowl.

2) The Eagles are currently just one game out of first place (behind a very suspect team).

Given the potential 2014 QB draft class, the long-term best interests of the team are probably served by losing, improving the draft slot, and using the draft to build the foundation of “Chip’s” team.

Unfortunately, given the profit-incentive and the general short-term incentives of NFL coaches, it’s too much to ask for the Eagles to NOT do everything they can to make the playoffs. That means when Vick is healthy, he plays, unless Foles comes back before then and remembers how to throw the ball.

There’s probably not a worse outcome for the Eagles this season than a 7-9 finish and missing the playoffs by a game. Sadly, that appears to be the most likely result at this point in the season. Note, if both Foles and Vick are out for a while, then this doesn’t hold (they won’t win many more games in that case).

– Kendricks had a very good game. Cox played well also. Have to end on a good note, so here it is. Pending review, of course, the 2 Eagles players that have the biggest potential for “foundation” status on defense (Boykin may work his way into this category soon) had good games. Let’s not get too excited, for reasons I mentioned above (bad offense), but it’s a good sign nonetheless.

P.S. I’m not ignoring the decision-making from Chip, I just realized that it probably needs its own post.

Eagles v. Giants: Week 8 Pre-Game Notes

Posted on October 27, 2013 by Brent

A win today and the Eagles are back at .500, and more importantly, might be back in a share of 1st place (the Cowboys play the Lions). I’m a little surprised at most of the analyst take’s on the game. For some reason, nobody seems willing to admit the fact that all available evidence suggests the Giants are a terrible football team. What evidence is that? Glad you asked.

– As I explained in the handicapping post, Football Outsiders takes a very dim view of the Giants. New York ranks 31st in total DVOA (-34.9%). For reference, the Eagles rank 20th, at -4.6%. So far this season, the Eagles have been the much better team.

– The Giants have just 6 sacks this season. This should be a huge red flag for anyone picking the Giants to win, because it mitigates the one factor that could make this game a toss-up…Vick’s health. Normally, if Vick can’t run, he’s lost most of his potency. However, if there’s no pass rush, it won’t matter. If the Eagles O-Line can do its job, the Giants will be forced to blitz, which SHOULD leave a lot of openings for the passing game.

– The Eagles defense can win this game by itself. I have no concerns remaining from last week’s terrible offensive performance. There were opportunities there, and Foles just missed them. That’s an indirect way of saying that the Eagles will score often today. Conversely, the Giants are on of the worst offenses in the league. The Eagles defense has struggled this season, but seems to be less of a disaster than it was early on. It’s still bad, but it can’t ask for a much easier matchup than this. The Giants are averaging just 67 rushing yards per game. Given their record, perhaps we should expect the Giants to have been forced to give up on the run fairly often. However, in that case we should see inflated pass stats. Instead, the team is averaging 260 passing yards per game, which ties them with the Eagles (they’re slightly ahead if we go to decimals). By itself, 260 passing yards per game isn’t bad (ranks 10th overall). But for the reason I mentioned above (losing a lot), it’s misleading and bad.

– Blanket Victor Cruz. The fast receivers should scare the Eagles much more than the big receivers. Specifically, Nate Allen trying to run with Cruz is a nightmare. Double-cover him every play. Normally, you’d be scared that Hakeem Nicks would then run wild, but have you seen him play recently? He’s either mailing it in or actually forgot how to catch a football. Either way, I’d make him prove it before shading any real attention his way. Rueben Randle is the actually bigger Non-Cruz concern here. He has 9 catches this season of 20+ yards, and is quietly developing into an actual threat. Look for him to be the “guy casual fans don’t know who blows up against the Eagles”.

– Vinny Curry time… Curry’s playing time takes a hit because he’s a liability against the run. Improving or not, he’s not the guy you want out there against a good rushing attack. As I said earlier, though, the Giants do not present that situation. Instead, they seem to be a perfect team against which to fully unleash Curry. Manning is a statue, and he’s makes foolish throws if you pressure him. Peyton Hillis will be the primary back, so let’s not get too worried about letting the Giants take advantage of Curry’s aggressiveness. I’ll gladly trade a couple of 8-10 yard runs allowed in exchange for having Manning’s pocket collapse every time he drops to pass. The key is that Hillis isn’t going to rip an 80 yard TD run, so the risk of playing Curry is less than normal.

That’s all. Eagles, if they don’t do something stupid like take a bunch of penalties or fumble the kickoffs, should win this game, and frankly, it shouldn’t be that close. If Vick isn’t 100%, than we might be in for a tight one, but unless he’s significantly hobbled, the only ones that can beat the Eagles today are themselves.

Eagles Rewind

Objective and Analytical Analysis of The Philadelphia Eagles and the NFL