In what is becoming a yearly tradition, today I am going to post the era-adjusted passer ratings from the 2019 season.

Passer rating is made up of four variables: completion percentage, yards per attempt, touchdown percentage, and interception percentage. The reason passer rating needs to be adjusted for era? Well, that’s pretty simple to explain.

When the formula was derived in the early ’70s, an average rating in each variable was achieved with a 50% completion rate, averaging 7.0 yards per pass attempt, a 5% touchdown rate, and a 5.5% interception rate. Since those numbers are wildly out of date, I came up with a formula that perfectly matches the intent of passer rating but ties the variables to the league average in any given season. You can get the formulas and read more background in the linked posts.

In 2019, the four averages were 63.5%, 7.22, 4.46%, and 2.30%, respectively. The big changes, of course, are in completion percentage and interception rate; yards per attempt is much more stable throughout history, while touchdown rate is actually slightly lower than it was in the ’70s.

One thing to keep in mind: these adjustments will not change the order of passer ratings in a given season. So Ryan Tannehill, Drew Brees, Lamar Jackson, Kirk Cousins, and Russell Wilson will remain your top 5 leaders; the way the formula works, it simply subtracts a fixed amount from each passer’s actual passer rating. In 2019, that amount was a whopping 23.7 points from each passer.

Below are the 2019 passer ratings:

Baker Mayfield had an actual passer rating of 78.8, which was about league average in the mid-1990s but was the second-lowest rating of 2019 among qualifying passers. This was not an awful season by historical standards: Mayfield completed 59.4% of his passes, averaged 7.2 yards per attempt, threw a touchdown on 4.1% of his passes and an interception rate of 3.9%.

For Mayfield, the dropoff in his second year is a bit reminiscent of another former first overall pick: Jim Plunkett.  As a rookie in 1971, Plunkett finished 11th in passer rating.  But like Mayfield, in his sophomore season, he had the second-lowest passer rating in the NFL.

There have been 90 quarterbacks who threw enough passes to qualify for the passer rating title in both their first and second seasons.  In that group, Plunkett had the biggest decline from his first to second season, and Mayfield ranks in the bottom 10.  The table below shows the full list, sorted by the biggest improvement from first to second year. The table is fully sortable and searchable.