Week 15 Bayesian Quarterback Rankings

Justin Herbert out, Lamar Jackson back on the rise, chaos at the lower end of rankings

You can find all the previous weeks’ versions of the Bayesian Quarterback Rankings here.

COMPARING GRADES AND EFFICIENCY

PFF grades aren’t part of the analysis, but I find it helpful to make not of how they align with EPA per play, as many contextual elements of quarterback play (drops, interception-worthy throws, easier throws that become big gains, etc) are part of the grading methodology, but aren’t accounted for in EPA. At the same time, I think EPA does a vastly superior job of weighing what is and isn’t important in points-based results.

We’re picking nits at this point in the season, but there was a little uplift for Dak Prescott versus Josh Allen in the top-right of the chart, with the former now materially higher PFF grade and EPA per play. Tua Tagovailoa is still in the vicinity of those two, but Patrick Mahomes has fallen a bit out of favor, at least in terms of EPA per play. Some of Mahomes’ struggles this year is not getting an uplift - more like a detriment - from receiver this year, which shows up in efficiency more than grading.

Brock Purdy is still the EPA king, and his PFF grade ranking has moved up from the late teens to 7th, or 5th if you remove two quarterbacks out for the rest of the season (Kirk Cousins and Justin Herbert). I’ll restate that the bigger the sample the more I believe EPA over grading, so I’m not surprised to see the gap between the two close in the direction of EPA, as we had a pretty good sample on Purdy career several weeks ago.

Another EPA vs grading battle to keep an eye on going forward is with Will Levis. After a strong comeback on Monday night, Levis’ EPA per play is now above average and not that dissimilar from those of Jared Goff and Matthew Stafford. His grading is the 7th worst of current starters. I’m cautiously optimistic, and so are the Bayesian rankings (see below).

WEEK 15 PROJECTED EFFICIENCY

These results are the ranking for the go-forward projections of quarterback efficiency this season. I also included the EPA per play rankings for each quarterback over the last five seasons (minimum 250 dropbacks in previous years, 120 in 2023) so you can see the evidence going into the projections.

Older data is decayed over time, so the 2023 EPA per play data matters more than those from pre-2020. That said, older data can’t be fully discounted, or else you miss bounce-back performers of great quarterback returning to form, like Aaron Rodgers in 2020 and 2021.

The injury parade continues, with Justin Herbert added to the list of elite quarterbacks out for the season. There was also a declared quarterback switch in Minnesota, with Nick Mullens starting this week and Josh Dobbs headed to the bench. The exclusion of Herbert in the rankings artificially boosts the “change” in ranking for all quarterbacks in the 5-32 range.