Field Position Persistence

As I mentioned a few weeks ago, there are several reasons to be hopeful that the Eagles can rebound quickly from this year’s poor performance.  After going through the stats it seems clear to me that this year the Eagles were a mediocre team will really bad luck (and a lot of injuries).

As evidence, I showed how both the offense and defense we actually ranked in the middle of the pack according to yards for/against.  A big difference, however, was the team’s net average starting field position, which was last in the league at -6.67 (So opposing teams, on average, started nearly 7 yards better than the Eagles.)  In fact, that was the fourth worst measure of any team over the past 5 years (’11 Colts/Chiefs and ’09 Lions were worse).

This measure is effected mostly by two aspects of the game, special teams and turnovers. The Eagles were terrible at both this year.  As I illustrated previously, though, turnovers are largely random, showing little persistence from year to year.  Therefore, since turnovers impact field position, we should expect little persistence in the Net Average Starting Field Position measure.

If this too is largely random, then we can expect both the Eagles offense and defense to perform better next year purely as a result of have less yards to go to score (or more yards to go for the opposition.)

Using the past 5 years, I charted each team’s Net Field Position against that team’s same measure the following year.  Here is the chart:

Screen Shot 2013-02-05 at 10.35.19 AM


The correlation value is 0.14.  So some persistence, but fairly small, which is what we thought we’d see.

Over the next few weeks there will be a lot of talk about things like coaching schemes and who stays/goes, but I doubt we’ll hear anyone say the Eagles could keep the same exact team for next year and have a good chance of finishing .500 or better as things like the fumble recovery rate revert to the mean (probably, it’s possible the team will be very unlucky next year but the odds of that are pretty small).

Other notes:

– The 49ers have led the league in net field position in both of the last two seasons.  Last year, the 49ers had the highest mark of the last 5 seasons, with a net value of 9.39, which is a massive advantage.

– Over the past 5 years, the Patriots have the best average (+4.13 yards).  The only other team above +3 is Atlanta (+3.44 yards).

– Detroit has the worst 5-year average, -2.73 yards.  Last year’s Colts had the worst measure for and individual season at -7.26 yards.

– The Eagles 5-year average is -.806 yards.

All data is from Football Outsiders.


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