Wednesday, December 29, 2010

Quarterback Rating

The NFL has a QB rating, a composite statistic that combines yards, pass attempts, completions, touchdowns, and interceptions. Unfortunately, it's kinda arbitrary. In an effort to fix that I present an estimated points added statistic, which includes all of the above.

The basis for EPA is that at any given point on the field a team has an average number of points they'll get. At their own 20, it's about 0, at their opponent's 20 it's around 4 (for first and 10). 15 yards adds about a point. A turnover at the line of scrimmage is then -4 points (so -3 for a 15 yard interception). Similar values can be obtained for the other achievements. Here's the components:
One yard: 1/15
Interception: -3
Touchdown: 3
Attempt: -2/5
Completion percentage-60 (average): completions/150
It doesn't make total sense at first, but the results do. Here they are:

Player EPA PPG Wins
Philip Rivers 160.54 10.7 4.01
Tom Brady 158.89 10.6 3.97
Aaron Rodgers 129.14 9.23 3.23
Drew Brees 104.64 6.98 2.62
Michael Vick 101.44 8.47 2.54
Peyton Manning 100.3 6.69 2.51
Matt Cassel 99.6 7.1 2.49
Joe Flacco 97.22 6.48 2.43
Matt Schaub 93.38 6.21 2.33
Josh Freeman 85.41 5.69 2.14
Ben Roethlisberger 79.82 7.24 2
Jay Cutler 78.63 5.62 1.97
Kyle Orton 74.99 5.77 1.87
Matt Ryan 71.58 4.77 1.79
Eli Manning 71.25 4.76 1.78
David Garrard 66.95 4.77 1.67
Carson Palmer 51.13 3.4 1.28
Jon Kitna 50.41 5.05 1.26
Ryan Fitzpatrick 43.86 3.38 1.1
Tony Romo 43.17 7.21 1.08
Jason Campbell 37.89 3.16 0.95
Donovan McNabb 30.22 2.33 0.76
Shaun Hill 24.14 2.42 0.6
Chad Henne 21.06 1.51 0.53
Alex Smith 20.9 2.09 0.52
Mark Sanchez 18.96 1.26 0.47
Sam Bradford 15.32 1.02 0.38
Kerry Collins 13.71 1.52 0.34
Matt Hasselbeck 7.29 0.52 0.18
Brett Favre 0.93 0.07 0.02
Derek Anderson -11.48 -0.96 -0.29
Jimmy Clausen -40.12 -3.35 -1

The best quarterbacks in the NFL are right at the top, as they should be. The PPG column accounts for some quarterbacks (Vick, Romo) not playing all their games. Most useful though is the wins column, which divides EPA by 40 (as shown earlier in the week) to get the expected wins added by a player over a replacement quarterback. For example, with his 4 wins added Tom Brady has taken the Patriots from the border of the playoffs to being the best team in football. Sounds like an MVP to me.
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1 comment:

  1. Thank goodness Cutler finished in front of Orton. I'd hate to think the 38 draft choices we traded away went for naught.

    Go Clones!

    (From the guy in Ames who knew you when you were in diapers)

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