Wednesday, February 3, 2010

NFL Wrapup: Pythagorean Projection vs Reality

Last summer, I did a series of posts on Pythagorean Projection (Part I, Part II, Part III, Part IV). As a follow-up to Part III, I present the Projected Wins for 2009 versus Actual Wins.

Note that the format for this table is slightly different than what I used in Part II. Here, the projection was used as a baseline, so a positive difference means a team exceeded its projected wins; a negative difference means a team fell short of its projected wins.

TeamActualProj. DiffComment
Jets 9 9.2 -0.2 New HC, QB
Eagles 1111.3-0.3
Seahawks 5 5.4-0.4 New HC
Chiefs 4 4.4+0.4 New HC, QB
Raiders 5 4.6+0.4
Browns 5 4.4+0.6 New HC
Patriots 1010.6-0.6 Brady back
Falcons 9 9.7-0.7
Lions 2 2.8-0.8 New HC, QB
Jaguars 7 6.2+0.8
49ers 8 6.9+1.1
Rams 1 2.6-1.6 New HC, injuries
Bears 7 8.7-1.7 New QB
Texans 9 7.3+1.7
Broncos 8 6.2+1.8 New HC, QB
Bills 6 7.8-1.8
Dolphins 7 8.8-1.8 Injuries
Cardinals 10 8.0+2.0
Packers 11 8.9+2.1 New defense
Panthers 810.1-2.1 Jake Delhomme
Vikings 12 9.2+2.8 New QB
Steelers 911.8-2.8 Troy Polamalu hurt
Colts 1310.1+2.9 Manning healthy all year
Chargers 1310.1+2.9
Ravens 911.9-2.9
Redskins 4 7.0-3.0
Cowboys 11 7.9+3.1
Giants 811.3-3.3 Eli injured
Saints 13 9.5+3.5
Titans 812.1-4.1 No more Haynesworth
Buccaneers 3 9.0-6.0 New HC, QB
Bengals 10 3.2+6.8 Healthy Carson Palmer

Broken down into the range used in Part I, we have:

Range # of Teams % of 32 Classification
0≤δ≤ 2 17 53.1%  Reasonably Close
2<δ≤ 4 12 37.5%  Moderately Close
4<δ≤ 8 3 9.4%  Wrong
8 00.0%  Yikes!

(Note that in Part I, the difference was expressed in winning percentage; here it is expressed in games won in a 16-game season.)


  • The teams are sorted by the magnatude of difference; teams that came very close to their projected wins are at the top, teams further away come further down the table.

  • In 2008 (c.f. Part II), 8 teams (25%) finished at least 5 games away from their projected win total, which (as I said) seemed likely to be an outlier year. Here we see teams much closer: only two finished more than 5 games away from their projected wins total.

  • There's also a case to be made for more gradual coaching changes. The Cardinals 2-game improvement (which could've been 3, if they had had something to play for in week 17), can be attributed to continuing improvements under Coach Whisenhunt. While the Redskins 3-game fall-off might be attributed to Coach Zorn losing his squad.

  • Those two or three extra wins that Favre (presumably) brought to the Vikings might not seem like a big deal out of context, but (this year) they're the difference between the #2 seed and being the last wildcard (or maybe eliminated in favor of the Falcons or some other team)