Just two quarterbacks finished in the top five in Win Probability Added (WPA) in both 2012 and 2013: Tom Brady and Andrew Luck.
I’ve long been a fan of the WPA metric, which calculates how much each play changes the likelihood of a particular team winning. From Brian Burke, the founder of Advanced Football Analytics (formerly Advanced Football Stats):
“The model created here at Advanced NFL Stats uses score, time, down, distance, and field position to estimate how likely each team will go on to win the game. For example, at the start of the 2nd quarter, a team down by 7 points with a 2nd down and 5 from their own 25 will win about 36% of the time–in other words a 0.36 WP.
“On that 2nd down and 5, let’s say there is a 30-yard pass, setting up a 1st down and 10 on the opponent’s 45. Now that team has gone from a 0.36 to a 0.39 WP. The WPA for that play would be +0.03.
“If instead the quarterback throws an interception returned back to the line of scrimmage, the opponent now has the ball at the 25, giving the trailing team a 0.28 WP. The WPA for the interception would be -0.08.”