Joe Montana. Steve Young. Yelberton Abraham Tittle. Some of the best quarterbacks to ever set foot on an NFL field played for the San Francisco 49ers, but none did what Brock Purdy has done this season.

You want wins? Purdy is one of only three rookie quarterbacks since the merger to start five or more games and go undefeated as a starter. The two others played for the Steelers: Mike Kruczek in 1976 (6-0) and Ben Roethlisberger in 2004 (13-0). Both rookie quarterbacks’ teams went on to play in the conference championship.

Are touchdowns more your thing? Only Deshaun Watson had a better TD rate in his rookie season (9.3 percent vs. 7.6 percent for Purdy), and Hall of Famer Dan Marino checks in at a distant third (6.8 percent). 

Perhaps you prefer a measure of overall efficiency? Purdy’s passer rating of 107.3 is the best ever for a rookie with 50 or more pass attempts. Or maybe you don’t like raw passer rating (I can’t really fault you). Purdy is also tops all time in rookie Passer Rating Index,¹ which adjusts for player era, beating out Marino by 3 points (128 vs. 125). He’s also first in adjusted yards per attempt index, besting Roethlisberger by 1 point (127 to 126).

And Purdy did all of this after being picked dead last in the 2022 draft? Somebody make it make sense.

Starting the year as the backup quarterback to Jimmy Garoppolo, who was himself the backup to Trey Lance, Purdy’s eventual opportunity was part of a trend that shaped the league in 2022. Sixty-eight quarterbacks started at least one game in 2022 — the second-most starters used in a season in NFL history, according to ESPN’s Stats & Information Group. 

Due in part to all the injuries, teams attempted passes at the lowest per-game rate in 13 years, and that lack of passing led to teams posting the fewest passing yards per team game (218.5) over that period. But it wasn’t just passing volume; quarterback efficiency also suffered. Leaguewide adjusted net yards per pass attempt dipped below 6.0 for the first time since 2017, another season notorious for the number of injuries to top QBs.

Yet despite being a third-string, seventh-round talent — just the sort of player you’d expect to contribute to the leaguewide QB slump — Purdy transcended the league’s environment and strung together five games of production that is unprecedented in league history. It’s difficult to overstate just how surprising this is.

As a point of comparison, consider the case of Watson, a quarterback who missed most of the past two years due to a suspension stemming from accusations of sexual misconduct by more than two dozen women. It shouldn’t be surprising for even a formerly elite player to have trouble playing at a high level physically and mentally after a layoff of that length. That makes Watson’s return late in the season a reasonable comp for the hurdles Purdy had to overcome when his number was called.

And while it’s not a perfect comparison — the 49ers defense is superior to that of the Browns, and Kyle Shanahan is a better coach than Kevin Stefanski — it’s pretty clear that coming into the year, most would have bet on the former All-Pro first-rounder putting up better stats than whomever Mr. Irrelevant wound up being.

Instead, over the last five games of the regular season, Purdy bested Watson in every meaningful statistical category.

Remarkably, Purdy’s YPA, passing touchdowns, TD-to-INT ratio and off-target throw percentage either tied for or led the league over that period. Meanwhile Watson’s 19 sacks — and never forget that sacks are a QB stat — was the highest total in the league over the final five weeks.

All of which is to say that being a quarterback in the NFL is hard, even if Purdy somehow made it look sort of easy. And maybe that’s because, well, it kind of was. There’s evidence on tape that Shanahan did everything he could to make the game as simple as possible for his rookie starter. Purdy’s best plays by EPA came on calls like rollouts, which gave Purdy defined, half-field reads, or on passes to running back Christian McCaffery and tight end George Kittle that featured more yardage after the catch than through the air. There were even wild orbit motion, double-fake passes with a “Y-leak” thrown in that went for scores.

Still, Shanahan’s genius for scheme only explains so much. Eventually Purdy had to stand in the pocket, process the defense past his first read, and deliver the ball downfield on time and on target.

Those are the throws we expect NFL starters to make — throws that teams draft QBs in the first round to execute. The fact that Purdy made them with regularity when the league took 261 players before him is revealing. Not even the 49ers — the team that ultimately took a chance on Purdy (with its ninth selection of the draft) — can escape embarrassment completely. After all, if any QB can run Shanahan’s system, why spend three firsts and a third-round pick to trade up for Lance just a few years ago?

The truth is, no one really knows anything about projecting quarterbacks to the NFL. If they did, Brock Purdy would be impossible. Instead, the Niners are 9.5-point favorites over the Seahawks this weekend with a starting QB who was drafted after four punters and a placekicker. And instead of impossible, Purdy and the Niners somehow appear inevitable. 

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