This is a new post, trying to get across the relationship between the AY/A stat and scoring (these stats are simplified expected points models)..
Adjusted yards per attempt or adjusted expected points per attempt?
Because these models show a clearly evident relationship between yards and points, you can calculate expected points from these kinds of formulas. The conversion factor is the slope of the line. If, for example, I wanted to find out how many expected point Robert Griffin III would generate in 30 passes, that’s pretty easy, using the Pro Football Reference values of AYA. RG3′s AYA is 8.6, and 0.075 x 30 = 2.25. So, if the Skins can get RG3 to pass 30 times, against a league average defense, he should generate 19.35 points of offense. Matt Ryan, with his 7.7 AYA, would be expected to generate 17.33 points of offense in 30 passes. Tony Romo? His 7.6 AYA corresponds to 17.1 expected points per 30 passes.
Peyton Manning, in his best year, 2004, with a 10.2 AYA, could have been expected to generate 22.95 points per 30 passes.
This simple relationship is one reason why, even if you’re happy with the correlation between the NFL passer rating and winning (which is real but isn’t all that great
), that you should sometimes consider thinking in terms of AYA.