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

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.


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”…