The greatest passers of all time

Adjusted for the era.

The NFL’s Passer Rating statistic has always been controversial. Its critics claim it doesn’t account for the true efficiency of a team’s passing game because it ignores sacks (and yards lost from sacks). It also has curiosities. For example, a 77.5 completion rate is as good as a 100% completion rate. At The Data Jocks, writer jdashbrock noted, “Two players with vastly different stats — one could even be noticeably better than the other! — can be labelled as both having perfect games by passer rating.”

Nevertheless, Passer Rating has historically been shown to correlate with team success. In 2011 Kerry Byrne reported that Passer Rating differential (a team’s offensive passer rating minus its defensive passer rating) is almost as reliable as scoring differential in identifying winners.

I kept track of passer ratings during most of the 2021 season, discovering that the team with the higher passer rating in the game won 79.6 of the time. Teams that won the turnover battle won 79.2% of the time during the same span. I speculated (with the confidence of common sense) that interceptions were the key factor in both stats.

I’ve wondered how to compare passers from different eras who operated under different league rules and playbook schemes. For instance, the league average passer…