Week 5 Luck-Adjusted Quarterback Efficiency

Adjusting for the high-variance aspect of value to get a better measure of quarterback play

Josh Allen jumps into the top-2 in adjusted EPA, justifying his leading MVP odds

We’re almost a quarter of the way into the NFL season, with impressions on quarterbacks, young and old, forming with increasing certainty. The old #QBWinz argument is a big issue already, but there are also a number of massively impactful plays happening each week that might not be well correlated to quarterback play. But there are a number of other elements of quarterback efficiency - directly affecting team performance - that are more dependent on luck (variance) than skill.

I aggregated many of those luck-based elements, with additional factors like receiver skill and scheme ability to generate yards-after-catch, in my Adjusted Quarterback Efficiency (AQE) metric. The “Open” metric used to measure receiver talent and its affect on quarterbacks isn’t available yet (Hopefully soon: get on it ESPN!), but I can use EPA data from nflscrapR and charting data from FTNData to measure the effects of other elements.

The measures that I believe are most luck-based and part of this analysis:

• Interceptions: FTNData tracks “interception-worthy throws”, which I compare to actual inteceptions on a play-by-play basis, and also adjust for expect interception return. Longer INT returns have a dramatic effect on the EPA, whether the quarterback’s fault or not.

• Drops: I calculated the expected drop rate for throws, based on location, and compared them to actual drops and determined the EPA lost/gained.

• Fumbles: Whether a fumble is recovered by the quarterback’s own team or not can turn a slightly negative play into massive loss. I look at expectations for recovery based on different types of fumbles, and whether the quarterback himself recovers the fumble or a teammate (luckier).

• Defensive Pass Interference: There are so many underthrown balls that turn into big DPI gains that need to be recognized as partially luck. By their very nature, DPIs are not “open” receivers with the coverage defender close enough to affect the receiver.

• Strength-of-Schedule: This is the one element that is most difficult to judge this early in the season. With three games played, a great offense can have a bigger affect making the defenses they played look “bad”, and vice versa, than might be the truth. But it still matters.

• Weather: Based on expected EPA gains/loss versus average in different elements, based on wind, humidity and temperature.

If you want more details on many of the calculations, check out the Adjusted Quarterback Efficiency (AQE) primers from last season.

• AQE introduction

• Update to 2.0

• Updated to 3.0

You can also check out the first installment of the Luck-Adjusted Efficiency numbers from last week (free post).

2023 LUCK-ADJUSTED RESULTS

The plot below shows each quarterback who has dropped back to pass 80 times this season. There are two points for each quarterback: 1) The team-colored dot for the actual EPA per play the quarterback has this season and 2) The quarterback headshot representing the adjusted quarterback efficiency (EPA/play). There is also a team-colored line linking the two on each row.