How much of Brock Purdy's 105.6 passer rating belongs to Brock Purdy?

Brock Purdy's career passer rating is 105.6.

That is first in NFL history among quarterbacks with at least 1,500 regular-season attempts, the minimum for the career list. He reached it on his fifth pass against Washington on Monday night. Lamar Jackson is second at 102.7 and Aaron Rodgers third at 101.8.

Purdy has 1,524 attempts. Jackson has 2,984. Rodgers has 8,976. A list that ranks those three on one number is mostly a statement about sample size, and the useful question is how much of Purdy's number would survive a bigger one.

Most of it.

Start with the league, not the list#

Passer rating has inflated for two decades. The league as a whole rated 77.2 in 1999 and 91.0 so far this season. A 105.6 compiled from 2022 to 2026 is worth less than a 105.6 compiled in 2005, so the fair comparison is each quarterback against the league in the seasons he actually played, weighted by his attempts.

Purdy's seasons carry a league average of 90.7. He is 14.9 points above it.

I ran the same measurement for every quarterback who entered the league in 1999 or later and reached 1,500 attempts, n = 81, at the exact game each one crossed the line.

Read down from the top. The median quarterback in the group qualified 0.2 points below the league, which is roughly what an ordinary starter looks like. Purdy is second of 81, and the gap between him and Rodgers is smaller than the gap between him and Mahomes.

Two of the eight were also first on the career list the day they qualified. Mahomes arrived in November 2020 at 110.7 and was still first at the end of 2022. He has not been first at the end of a season since. Rodgers arrived level with Philip Rivers at 97.3 in November 2010 and was alone in first by the end of that season. Mahomes is now at 100.8 and fifth. That is the precedent the list offers, and it is not a reassuring one.

How much of it is the offense#

The obvious objection is Kyle Shanahan. His offense produces open receivers and yards after the catch, and Purdy has played in no other.

The cleanest control available is everyone else who has thrown in it. From 2017 through Monday, quarterbacks other than Purdy threw 3,458 regular-season passes for San Francisco and rated 92.0, which is 1.3 points above the league over the same seasons. Jimmy Garoppolo alone threw 1,632 of them and rated 99.2, which is 8.9 above. Purdy, in the same offense, is 14.9 above.

So the offense has been worth somewhere between a point and nine points to the quarterbacks who passed through it, depending on who they were. Purdy is six points clear of the best of them. The confound that worries me most is the cast: Christian McCaffrey arrived in October 2022, seven weeks before Purdy's first start, and no comparison inside one franchise can separate a quarterback from the players around him.

The yards after the catch are smaller than the reputation. Purdy's completions have gained 5.6 yards after the catch, against 5.2 for the rest of the league since 2022. Give him the league's rate on all 1,038 of his completions and his career rating falls from 105.6 to 104.4. That is 1.2 points.

The bigger share of his yards comes in the air. His completions travel 7.0 yards past the line before the catch, against 5.7 for the league. As a share of his passing yards, yards after the catch rank 26th of 31 quarterbacks with 1,000 attempts since 2022.

Completion percentage tells the same story from another angle. The nflfastR model estimates how often each throw should be caught from its depth, its location and the situation. It expected Purdy's passes to be caught 66.5 percent of the time, slightly below the league's 67.2, which says his throws have not been easier than average. He has completed 4.0 points more than expected per attempt (n = 1,471 throws the model grades), second of 29 quarterbacks with at least 1,000 since 2022, behind Joe Burrow at 4.3.

The scheme tells you where he throws. It does not explain how often the ball arrives.

What 1,500 attempts is worth#

The remaining question is the sample. A quarterback is never measured more flatteringly than the day he qualifies, because a hot start is part of how a young passer gets to 1,500 throws in the first place.

Here is what the ten who qualified furthest above the league did over their next 1,000 attempts, n = 969 to 995 attempts each.

As a group they were 12.2 points above the league at 1,500 and 9.7 above it over the next 1,000. They kept about four-fifths of the margin. The range inside that is enormous: Rodgers won the MVP the next season, and Palmer and Watson fell to the league average.

Across all 55 quarterbacks with enough attempts afterward to measure, the margin at 1,500 predicts the next 1,000 reasonably well, a correlation of 0.58. The fitted line keeps about 65 cents of every point above the league, then adds 1.7 points. For Purdy that line says about 11 points above the league from here, which is about 102 at this season's league average.

A 102 is still an excellent quarterback. It is also lower than Jackson's current career mark. Throw 1,000 more passes at that level and Purdy's career figure settles near 104.3.

The call#

Purdy has rated 118.1 on 171 attempts this season. His career number moves slowly now, a few tenths a game, and it moves up only when he is better than 105.6.

Brock Purdy's career passer rating, on NFL.com's career page, is below 106.0 after the 49ers' last regular-season game, at Arizona on Jan. 10. To clear it, he has to rate about 108 over the rest of the season. He has done better than that over a full season once, in 2023 (113.0 on 444 attempts), and he is doing it now. He has also rated 96.1 and 100.5 in the two seasons since. A missed start helps the call, because the number freezes below the line.

Check back on Jan. 11.

Sources: NFL.com career statistics for Purdy, Jackson, Rodgers, Burrow and Mahomes; Pro Football Hall of Fame all-time passer rating list (the 1,500-attempt qualifier); nflverse weekly player stats, 1999 to 2026, and play-by-play, 2022 to 2026.