49ers Film Room: What kind of quarterback is Brock Purdy? Part 1
Is Brock Purdy a game manager? Is he a system quarterback? Is he a playmaker? Is he all three of these? We'll seek answers from the stats and film to address each narrative.
I’m just going to get this article out of the way since it’s likely the one that will cause the most heartache in this series. I don’t think Brock has a case to be the NFL MVP and it has nothing to do with his supporting cast as is so often claimed. More on that later though.
As the title of this article suggests, Brock Purdy is whatever you think he is. Game manager? Yes. Playmaker? Also yes. System quarterback? Sure, why not.
The truth is, he is ALL of those things right now. And that is perfectly fine. The blend of all three currently has the 49ers in their franchise’s eighth Super Bowl appearance, set to take on the Kansas City Chiefs in a rematch of Super Bowl 54.
Despite all of that, Brock Purdy has become sort of a litmus test for how we view the quarterback position, what we think a quarterback is responsible for versus what they are actually responsible for and what we think quarterbacks can control versus what they actually can control.
It begs the question though, if Brock were a high round draft pick, would he get this much scrutiny?
I’ll be the first to admit, I was hugely skeptical of Purdy coming into this season off of a major injury. My rationale was that he was not doing anything noteworthy last season that Jimmy Garoppolo wasn’t doing. I was partly wrong about that. He made plays and throws Jimmy couldn’t or wouldn’t make.
However, there were good reasons to believe that the explosion in offensive production, backed up by film and data, in 2022 were primarily due to the introduction of Christian McCaffrey into the offense and a defense that generated more short fields after their bye week by doubling their turnover production.
But that isn’t the case this season. Outside of the normal box score stats, Per Pro Football Focus (PFF), Purdy led the NFL in passing grade on deep throws (throws 20+ air yards downfield), is ranked 7th in big time throws at that distance (PFF), 5th overall in big time throws (PFF classifies a “big-time throw is best described as a pass with excellent ball location and timing, generally thrown further down the field and/or into a tighter window), is 2nd in the NFL in completed air yards per pass (per NFL NextGenStats), and leads the league in EPA/play (per RBSDM).
Purdy does not get enough credit for what he’s done and how he’s performed largely because of the skill talent around him. The above throws are big time throws as classified by PFF. There is an element to them in that yes, they are completions to top tier NFL talent. But the throws themselves are perfect throws. Should he be punished because the talent around him always catches these passes? Certainly not.
Right now, opinions are split between two camps: one that says he’s in the top 5 or 10 conversation among the league’s best quarterbacks, the other camp that thinks he’s at best a middling quarterback propped up by the roster and coach around him. Because of this, he largely won’t get credit for anything because of a three game stretch where the 49ers lost three games in a row while Trent Williams and Deebo Samuel were out and where Brock threw 5 interceptions and had 6 total turnovers.
He could not lead them to comeback victories, though to be fair to him, Jake Moody missed the game winner in Cleveland. But to be fair to Jake Moody, Purdy’s play in that week 6 game partially put them in that hole. Until the playoffs, he was not able to lead a comeback victory.
Back in week 16, Brock threw four more interceptions, effectively ending his MVP campaign. Although he largely didn’t play well for three-and-a-half quarters versus the Packers in the divisional round, he still led a game-winning drive and hit a couple of throws he needed to hit to lead them down the field to a win.
And in the NFC Championship game, he had an interception and another that was dropped, both bad passes. The interception highlights his physical limitations as a passer more than anything. Despite all that, he played well enough in that game and led a massive second half comeback to punch their ticket to Las Vegas.
Purdy as a litmus test
Purdy is a litmus test for how one views the game of football. If you value the results on the field, the box scores, etc., over everything else, then you likely viewed him as the NFL MVP, and still do. After all, the NFL is largely a results-driven business and the other candidates don’t have the stats.
Currently, Purdy is an MVP candidate with teammate Christian McCaffrey, and quarterbacks Josh Allen and Lamar Jackson. Of the the three quarterbacks, Lamar Jackson doesn’t have the total touchdowns and Josh Allen led the league in interceptions.
And there may be no more of a scrutinized candidate than Dak Prescott, who comes under the microscope constantly for every little thing Dallas does. Though to be fair, Dak’s resume doesn’t include the types of wins that the above quarterbacks have anyways and he’s not a candidate.
But if you value process over results, Jackson and Allen might be the favorites to win over Purdy and McCaffrey as there are not many more players more valuable to their own teams than those two quarterbacks.
The Ravens, since Lamar entered the league, are the league leaders in rushing EPA per play since 2018. It’s easy to correlate Jackson’s rushing ability to their run game success. They are always +1 in the run game with him.
Josh Allen was the 3rd overall quarterback in EPA per play in the 2023 regular season and he did that with subpar talent at the skill positions outside of Stephon Diggs. To be fair, Purdy is the #1 quarterback by EPA but the situations are different. That does not take away from what Purdy has done this season but it is an acknowledgement that those other two did more with less around them.
Those teams wouldn’t have sniffed the playoffs without those quarterbacks. Would the 49ers stay competitive with Darnold? Yes, if the first half of the week 18 game is any indication. Maybe not on the level Purdy has kept them, but competitive nonetheless.
But that’s not an indictment of Purdy. Far from it. If anything, Purdy has raised the level of play of the offense for the 49ers far more than his predecessors ever did under Shanahan. For one thing, on outside of the pocket throws (excluding play action), Jimmy Garoppolo ranked 16th in grading in 2022. In 2023, Purdy ranked 7th. On scrambles, Purdy registered 17 scrambles that went for 15 first downs, 88%.
The flip side of this is while Purdy is playing exceptionally well overall and has the gaudy stats and big time throws, there’s another side that is worth reporting on that until now has been largely taboo. To understand why the skeptics aren’t convinced he’s anything more than a system quarterback or a skill talent merchant or a passenger on the bus, we have to take a look at the primary reason they aren’t convinced: that is the subject of his on-target throw rate per Sports Info Solutions (SIS) and “turnover worthy play” rate per Pro Football Focus (PFF).
Through their five game win streak to start the season, Purdy ranked 9th in “turnover worthy play rate” (TWP) and jumped up to 6th through week 8 after their 3-game losing streak. In weeks 10 through 15, he dramatically dropped his TWP rate over the course of those six games to 1.1% yet only threw two passes considered “turnover worthy.”
That changed in week 16. He recorded two TWP’s despite throwing four interceptions, had previously tossed two interceptions in recent games. One might argue that TWP’s are a useless or pointless stat to track or cite but they are a context-driven stat. They track passes that hit a defender in the hands that have a good chance of being intercepted, whether it was or not. So not all throws are turnover worthy.
Purdy’s first interception versus Baltimore highlighted as much about his physical limitations as it did about his decision making. According to Shanahan after the game, he stated that Purdy read the coverage wrong. Then he tried to fit a pass in over the middle in compressed space that he was late throwing. This is a only a few quarterbacks can throw and get away with.
The play call is double post concept to the two receiver side with Deebo in the slot and Brandon Aiyuk outside with Deebo on the crosser and Aiyuk running the dagger. George Kittle and Kyle Juszczyk are aligned on the offensive line in a closed nub formation to the right. Christian McCaffrey is the running back who swings out wide left post snap.
The Ravens are in cover-6, quarters coverage to the passing strength and cover-2 to the closed side of the formation. Safety Kyle Hamilton (No. 14) is the cover-2 safety to the offense’s right.
There’s no deep route challenging Hamilton on that side of the field so he’s content to sit and watch the routes develop and key’s on Purdy reading right to left. The primary side of this concept is the premier look versus the quarters side. The split safety coverage shell can squeeze the inside deep crosser/post from Deebo and leave the outside post 1-on-1 with the corner.
Purdy drops back, sees split safety coverage, and comes back to Deebo too late. He threw the pass too far inside with Hamilton squeezing the route from the opposite hash. He’s able to step in front of the route for the interception.
Shanahan stated post game that Purdy misread the coverage. I also think he was late on the throw and think he had a chance to hit Aiyuk as the second in that progression. Either way, there was no reason for a risky pass across the middle like that.
In fact, this hybrid quarters coverage shell (cover-6), and quarters across the field (cover-4) gave Purdy trouble all season. He ranked 26th in the NFL in EPA per play against cover-4 and cover-6 combined. His worst coverage by itself was cover-6, where he had his lowest EPA per play of the season.
He faced these split safety coverages on 20 pass attempts of his 39 in the divisional round versus Green Bay.
On the first drive of the game, he nearly threw a pick-6 to safety Darnell Savage while trying to throw a dig route to Brandon Aiyuk. The only thing preventing a score here by the defense is Savage dropping the pass. Purdy didn’t recognize the safeties sitting back. Instead, he was reading the movement of the middle linebacker and thought he had a throwing window.
But Aiyuk’s route was never going to come open. The decision is a baffling one. He had time to survey the field and has a clean pocket where he isn’t under any pressure.
Against Detroit, he threw an interception on a play he should have just taken the sack on but he forced this throw in the face of pressure and a collapsing pocket. To make matters worse, it does appear that his hand got hit on his follow through, but that is more of a physical limitation that he’s not able to fight through than anything else.
Are his turnover worthy throws a problem? This season they largely weren’t. In weeks 1-9, Purdy ranked 19th in on-target throw percent and by week 18, improved to 12th overall. In TWP’s, per Pro Football Focus, by week 9, Purdy ranked 32 out of 37 qualifying quarterbacks with a 5.1% TWP rate. By season’s end, he finished 24th out of 45 qualifying quarterbacks at 3.4%. That’s a dramatic improvement though still in the bottom half of the league.
TWP’s give us context on poor decision making or bad ball placement and allows us to get the full picture of a player. Defenders failing to catch passes the quarterback throws to them doesn’t absolve the quarterback of a poor decision or inaccurate pass. These data points suggest a pattern and that we shouldn't be surprised when turnovers happen. Of course they were going to happen, the predictors were always there.
They also give us insight into his next concerning metric: on-target throw percent and catchable throw percent, two measures of accuracy. Per Sports Info Solutions, his 75.1% on-target rate is good enough for 13th in the NFL, near the middle of the league. That’s still 2.3% lower than Jimmy Garoppolo’s on-target rate with the 49ers from 2017 to 2022. Purdy’s catchable rate, 85.7%, is 20th in the NFL. Garoppolo’s from 2017 to 2022: 87.3%. He’s accuracy just isn’t what it’s made out to be.
The conundrum here is none of that is why he’s succeeding in year 2 as the 49ers starter. Quite the contrary, as I’ll in the second article, he’s giving the 49ers a boost in other areas that Garoppolo just couldn’t give it in. Quarterbacks aren’t just throwers of a football. As I alluded to earlier, it largely centers on what we think quarterbacks are supposed to do down to down, series to series and how that generates discussion in the game manager versus system quarterback versus game changer debate, something we’ll take a look at in part two of this series.
It isn’t that he’s doing things other quarterbacks aren’t doing. It’s that he’s doing things other quarterbacks do but isn’t getting his share of the credit for.