More reasons for hope…examining turnover luck and field position.

I’ve been digging through a lot of data while putting together a database that we can examine for interesting information.  In the process, I’ve come across some encouraging news for the Eagles heading into next year.

First, a few stats from this year:

- According to Football Outsiders, the Eagles ranked 14th in yards per offensive drive (35.51 ypd).

- The team also ranked 14th in defensive yards per drive (30.50 ypd), or yards allowed per drive.

Neither of those is great, but if you looked at nothing besides those measures, you’d be very surprised that the team finished 28th in the league.  Now let’s look at two related stats (also from Football Outsiders):

- The Eagles ranked 24th in offensive points per drive (1.54).

- The team ranked 28th in points allowed per drive (2.21).

Those numbers make it a bit easier to see why the team’s record was so bad.  But why the discrepancy?  Why were the Eagles so much worse than almost every other team at converting yards to points?

It will be news to almost nobody that the answer lies mainly in two stats, turnovers and field position.  However, most people don’t fully appreciate just how bad the team’s performance was in those areas this year.  Here are a few more stats from this year before we get to the hopeful part (I promise there is one).  Over the past ten years:

- Many people know the Eagles had the worst TO differential of any team (-24, tied with this year’s Chiefs and the ’04 Rams).

- However, a big reason for this was that the team lost 22 fumbles this year.  Over that time frame, only the ’07 Ravens were worse.  Conversely, the Eagles threw 15 interceptions this year, which is nothing to get too upset over.

-  The team only had 13 takeaways, behind only the ’06 Redskins for least since 2003.

-  The Eagles average starting field position (25.19 yard line) ranked 27th in the league this year.

- Eagles opponent’s started with better field position (31.86 yard line) than anyone else in the league.

- Combined, the net result of  -6.67 yards was by far the worst difference in the league (St. Louis was next with -5.87.)  In clearer terms, the Eagles had to go nearly 7 more yards each drive than their opponents in order to find the end zone or field goal range.

So we have a team that lost more fumbles and created fewer turnovers than almost any other team in recent history.  That, along with poor special teams play, led to the worst field position differential in the league by far, which goes a long way towards explaining why the offense and defense could finish in the middle of the pack for yards per drive without scoring/preventing points.

It also explains how Nick Foles could look good (i.e. move the offense) without better results.  He almost literally could not have received less help from the rest of the team by way of field position or extra possessions.

So where’s the hope I promised?  For that we have to re-engage our old friend, the correlation analysis.  Here’s what it tells us:

- Earlier this year, we looked at individual player fumbling rates and found that most of it is the result of luck.  In other words, be very skeptical whenever you hear that a player has a “fumbling problem”.  Therefore, it should come as no surprise that the same holds true for teams.

Using every team’s performance from the last ten years and measuring lost fumbles from one year to the next, I derived a correlation coefficient of .0837 (very weak).  This means that although the Eagles had a historically bad year (losing 22 fumbles), there is no reason to expect next year will be anywhere near as bad.

A little mean reversion will go a long way towards improving the TO differential. (Also, see the fumbling recovery rate post from earlier this year.)

- Similarly, I ran the same analysis on takeaways, and found a similarly weak correlation coefficient of .0838.  Turns out, there is very little persistence in takeaways as well.  Therefore, we have no reason to expect the Eagles to be as impotent next year when it comes to creating turnovers as they were this year.

For those of you that are skeptical, here is the data chart.  Takeaways are on the Y axis, with takeaways the following season on the X.

Screen Shot 2013-01-08 at 1.00.02 PM

Note:  I am not suggesting that both takeaways and fumbles are COMPLETELY luck.  At the margins, there are players who are clearly good at not fumbling and similarly I expect that there are a few teams/players that are persistently good at forcing turnovers.  However, overall, those teams/players are exceptions.

Wrapping up, by examining data from the last 10 years, we can see some evidence that suggests that this year, the Eagles were both a bad team AND a very unlucky one.  While there’s no guarantee they become a good team next year, I feel comfortable saying it is likely they won’t be as unlucky.

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