49ers film room: Breaking down Brock Purdy's 4 interceptions versus the Ravens and other thoughts
Brock's interceptions were both unlucky and point to larger issues his production has largely hidden through 16 weeks.
The much anticipated game of the season, 49ers at home versus the Ravens on Christmas Day on Monday Night Football, did not go as expected as the 49ers, fresh off of a 6-game win streak since their bye week, dropped a tough one 33-19.
Overshadowing everything was Brock Purdy’s four interceptions, three of which came off tipped passes that were just more unlucky than anything. It was just the second time all season that he also thrown for zero touchdown passes, the other being week two at Los Angeles.
The Ravens offense and defense controlled the game pretty convincingly too, turning three of Purdy’s turnovers into points of some type on shortened fields. They also marched the length of the field three times on offense to score points and were aided by some special teams and defensive penalties in the process.
The 49ers looked prepared. They moved the ball well on the ground and Purdy, outside of his first interception, was throwing the ball well too. But they still could not overcome the bad turnover luck, which was the dam waiting to burst in the Purdy era. Even though three of the interceptions can just really be attributed to bad luck on tipped passes more than anytihng, the turnover regression was bound to happen at some point.
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 per Per Pro Football Focus (PFF). In weeks 10 through 15, he dramatically dropped his TWP rate over the course of those six games to 1.1% and only threw two passes considered “turnover worthy.”
That changed in week 16. He recorded two TWP’s despite throwing four interceptions, and 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.
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. Those passes still exist on tape and if those data points suggest a pattern, which they do, then we shouldn't be surprised when turnovers happen.
But which interceptions in week 16 can the quarterback actually be held responsible for and which ones can we say he’s not responsible for? I would say one and half are on Brock, the others are just either bad luck or were caused by other factors such as poor pass protection. We’ll also look at two more passes that should have been interceptions but weren’t.
1st interception: 100% on Purdy
Purdy’s first interception was the wind that was taken out of the sails and seemed to set the tone for the entire half after that. The offense drove down to the 15 yard line after a 58-yard catch on third down by George Kittle and another 13 yard catch from Kittle on consecutive plays to open the game.
The play call is a double post concept to the two receiver side with Deebo in the slot and Brandon Aiyuk outside. Deebo is running the inside post and Aiyuk is running the outside post. 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 eye’s 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 post from Deebo and leave the outside post 1-on-1 with the corner.
Purdy drops back and sees split safety coverage and comes back to Deebo too late and throws 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.
2nd interception: tipped ball bad luck
Interception #2 was just bad luck with Purdy throwing an alert route on a run play. The 49ers have run several variations of this run-pass option (RPO) over the years from under center with the quarterback making a pre-snap read to throw versus a favorable edge matchup outside.
Purdy is reading the WILL linebacker who’s aligned inside the box and not in the throwing window. Defensive back Brandon Stephens, speaking to The Athletic’s Ted Nguyen after the game, stated that “If he realizes it’s a corner blitz, I know the quarterback is going to go to a ‘now’ with no one being outside. I just timed up the jump and gave our guy Marlo a chance to make a play on the ball.”
Right at the snap, Stephens came on the corner blitz. You can see in the still frame above that Purdy is peaking the blitz as he exits from under center.
He made the right read and decision here as Deebo is wide open with nothing but space to operate. Stephens timed the jump as Purdy threw and batted the ball up in the air to Marlon Humphrey.
Some might argue he made the wrong read or a bad throw because it was into a blitz but quarterbacks are taught to throw hot into the blitz and replace the leverage. What a quarterback cannot account for is knowing that the defender would tip the pass.
3rd interception: 50% bad luck, 50% George Kittle
On the very next drive, Purdy tried to keep a play alive by scrambling around and trying to make a play. The pass bounced off of Kittle’s shoulder pads up into the air to Kyle Hamilton.
The defense runs a cover-3 fire zone pressure with Hamilton blitzing off the edge and the mugged up linebackers Roquan Smith and Patrick Queen and defensive end Kyle Van Noy spot dropping off the line of scrimmage into underneath coverage zones.
When Purdy gets to the top of his drop, everyone is perfectly covered and there’s nowhere to throw the pass.
He scrambles around and tries to buy time to make a play but ends up rolling back to his right and throwing a pass back to the inside to Kittle who was covered by Humphrey. Kittle could either run straight across to open grass or come to the quarterback diagonally in a straight line but he takes a couple of steps to the inside before working back as the ball gets to him.
As a result, the pass is on his outside shoulder with Humphrey reaching across to break it up. Kittle was unable to get his hand free and the pass bounces off his chest up into the air where Hamilton catches it. Purdy took a lot of blame here but there was nothing wrong with throwing back inside. He was able to see the situation and decided to give Kittle a chance to make a play. It wasn’t like it was a pass into traffic.
4th interception: 50% Purdy, 50% pass protection
Purdy’s fourth interception and ensuing Ravens scoring drive all but put the game out of reach for any kind of comeback and Purdy was at least partially responsible for the outcome.
The play has Purdy looking to his right first for Brandon Aiyuk on a choice route then to McCaffrey on the front side on a choice route out of the backfield and Kittle on a deeper dig route to McCaffrey’s side.
The defense is in cover-6 again.
Purdy is an anticipation thrower so this ball should’ve come out as soon as he was checking Aiyuk in the progression. It’s not clear why it didn’t. He had Aiyuk in the zone between the linebackers for an easy throw.
He scans back to his left and looks for McCaffrey on the choice route out of the backfield, sees McCaffrey break inside, and is late throwing it.
Defensive end Travis Jones was able to basically shove Colton McKivitz aside and hit Purdy’s hand as he was throwing the ball. The result was a fluttering pass into the hands of Patrick Queen for the interception. McKivitz shares some blame for the outcome here due to a poor pass blocking rep but Purdy did have a chance to get the ball out on time within the structure of the play.
This isn’t the first time he’s had a tipped ball interception resulting from a missed read either. He had one in the Bengals game when he misread the RPO key to hand off and instead tried to throw a pass out on the edge after extending the play.
Off target throws are a concern
While the resulting interceptions were unfortunate, the larger concern with Purdy is the amount of passes he puts in harm’s way that could be interceptions. In this game, he had two more that could've been interceptions, one due to a bad throw and one due to a bad read.
On the first throw, the other play that PFF considered a “turnover worthy play,” Purdy’s pass deflected off of a Ravens defender when he tried to hit Willie Snead for a third down conversion.
The Ravens sent an edge pressure with Patrick Queen off the right edge of the offense while the backside concept has both Deebo and Snead on short slants over the middle.
The ball probably should’ve gone to McCaffrey since he’s the hot receiver to the side of the blitz. Even if he didn’t like that, Deebo is the better throw and we’ve seen Purdy consistently fade away from the pressure and deliver strikes. Snead was bodied off of his release right away and never had a chance to catch the ball.
This throw on the next drive didn’t count as a TWP even though the defender got his hands on it off of a deflection from Deebo.
This is just a bad pass that Purdy threw behind Deebo that Deebo deflected up to the receiver. Had this been an interception, we could comfortably place the blame on the quarterback for throwing a bad pass rather than just bad luck even if it’s not technically a TWP. The reason it’s not a TWP, according to PFF’s Jeff Deeney, was because any pass that bounces off of a receivers hands first isn’t usually going to be scored a TWP.
Outlook
This game ended Purdy’s NFL MVP conversation, though I never really believed, before this game, that he should win it anyways. But he won’t now because of how convoluted the narrative around MVP candidates has become. Every week it seems there’s a new frontrunner just based on how the previous week’s games went. This week it’s Lamar Jackson even though he doesn’t have the statistical output others have.
Nonetheless, Purdy did not play well by any objective measure. His on-target throw rate, according to Sports Info Solutions, was 27th among all passers in week 16 at 66.7%, which is lower than his season average through 15 weeks at 75%. Even at 75%, he was still ranked 18th in on-target throw rate. These are not how MVPs usually perform. And this is the world they live in with Purdy.
The question becomes how content are they living in a world where Purdy is such a high variance thrower. So far, this variance has cost them games in Cleveland and at home versus Cincinnati, though I wouldn’t put all those losses squarely on his shoulders.
The other more concerning thing to watch is how defenses play them the rest of the season and into the playoffs.
Currently, the 49ers are facing 61% single high safety coverages and Brock has shredded those coverages. It’s just easier to pass when teams load up to stop the run. They aren’t challenging him to beat them with the pass, as is often the conventional narrative with these kinds of data points, they just don’t have as many defenders in coverage in the areas the 49ers like to throw against those defenses.
In week 16 against San Francisco according to Sports Info Solutions, Baltimore played 78% zone coverage and 61% middle of the field open/split safety coverages against SF. In weeks 1-15, Baltimore played 60% zone coverage and 45% middle of the field open/split safety coverages. They broke their own tendencies to break the 49ers tendencies.
The 49ers saw more of the pass coverages they’re not as efficient at throwing against, split safety coverages (cover-2, quarters, cover-6) because defenders sit in the zones where they want to throw and can bracket certain routes with two deep safeties. The game tape is littered with that issue for the 49ers.
Fortunately, there isn’t really a team remaining on their schedule that can match the level of play or the specific gameplan of the Ravens, including in the playoffs, until they get to a potential rematch with the Ravens (or Browns for that matter). 49ers fans should hope Baltimore gets bounced if the 49ers are to make a run toward a Lombardi trophy. And hopefully Shanahan can find some answers to the coverages that plagued them in this game.