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.