49ers - Brock Purdy

davegilbertson

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Traditional QB rating is a lot like batting average in baseball, it tells a story, but not a very complete one. You need to start looking at things like EPA and other advanced stats. They incorporate so much more than traditional rating which is just a simple math formula based on attempts, completions, yards, tds, and ints.

On an EPA basis Brock was worth 25.2 total EPA and 0.72 EPA/play against Seattle, his best game of the year, but this week he was worth 3.2 total EPA and 0.09 EPA/play, which is in fact his worst performance of the year and a lot closer to several of his other games than last week was. (From weeks 13 to 18, Brock was a top 5 QB with an EPA/play of 0.207. ) Mahomes has one or two games close to that low. The others have all had a least a couple below that, if not games in which they produced negative EPA.
Does EPA factor in defenses faced. While I felt like it was clearly not his best game, it would've been a crazy good performance for him to put up his regular numbers against that D. Given how well Dallas was playing I thought Brock did well enough, extended drives and avoided disaster.
 
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PSYclone22

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Last night I heard multiple talking heads say that Purdy has hit his ceiling. That he's in trouble because he'd have to air it out and make plays to beat Philly since the teams are so evenly matched on both sides of the ball, but not QB.
If they mean air it out in the sense of not throwing short, he had the second highest Air Yards per Attempt in the Divisional Round at 8.5 AYA (how many yards down field his targets were). Allen was at 8.9 against CIN.

For the entire playoffs he's at 10.2 AYA, behind only Allen and Skylar Thompson.
 

PSYclone22

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Does EPA factor in defenses faced. While I felt like it was clearly not his best game, it would've been a crazy good performance for him to put up his regular numbers against that D. Given how well Dallas was playing I thought Brock did well enough, extended drives and avoided disaster.
EPA doesn't account for defense, but neither does passer rating. Adjusted EPA is a stat available on rbsdm.com/stats/stats and it accounts for defenses
 
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houjix

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Does EPA factor in defenses faced. While I felt like it was clearly not his best game, it would've been a crazy good performance for him to put up his regular numbers against that D. Given how well Dallas was playing I thought Brock did well enough, extended drives and avoided disaster.
EPA tends to be more agnostic towards the opponent and just factors in how much you improved the teams position during the game. Football Outsides and their DVOA does factor in some of that I think. But for reference, Dallas was the second best defense on an EPA basis for the regular season with the 49ers being first. However, the Cowboys were only 4th against the pass. The Eagles were actually the best passing defense in the league(4th combined) with the 49ers being second. So last Sunday and next are by far going to be the toughest defenses Brock will face.
 
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wenkeej

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Traditional QB rating is a lot like batting average in baseball, it tells a story, but not a very complete one. You need to start looking at things like EPA and other advanced stats. They incorporate so much more than traditional rating which is just a simple math formula based on attempts, completions, yards, tds, and ints.

On an EPA basis Brock was worth 25.2 total EPA and 0.72 EPA/play against Seattle, his best game of the year, but this week he was worth 3.2 total EPA and 0.09 EPA/play, which is in fact his worst performance of the year and a lot closer to several of his other games than last week was. (From weeks 13 to 18, Brock was a top 5 QB with an EPA/play of 0.207. ) Mahomes has one or two games close to that low. The others have all had a least a couple below that, if not games in which they produced negative EPA.
I haven't ever gotten deep into football "sabermetrics" but I assumed there would be a good way to evaluate an overall QB performance. Your comments just goes further to my point. Purdy has performed at a high level so far this season, and one down game against a top defense shouldn't all of the sudden change him to a glorified backup, especially when compared to other QBs in the league.
 

wenkeej

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EPA tends to be more agnostic towards the opponent and just factors in how much you improved the teams position during the game. Football Outsides and their DVOA does factor in some of that I think. But for reference, Dallas was the second best defense on an EPA basis for the regular season with the 49ers being first. However, the Cowboys were only 4th against the pass. The Eagles were actually the best passing defense in the league(4th combined) with the 49ers being second. So last Sunday and next are by far going to be the toughest defenses Brock will face.
It sounds like the 49ers might have a better chance to run the ball against the Eagles. If that's true, it could help open up a little more time/room for Purdy to operate. But you're right, this coming weekend will probably be just as difficult as last, if not more. He navigated last weekend and came away with a win so I can't see why he couldn't this weekend.
 

PSYclone22

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I haven't ever gotten deep into football "sabermetrics" but I assumed there would be a good way to evaluate an overall QB performance. Your comments just goes further to my point. Purdy has performed at a high level so far this season, and one down game against a top defense shouldn't all of the sudden change him to a glorified backup, especially when compared to other QBs in the league.
Here's some of the more analytical metrics from week 14 through the Divisional Round:

1674598013701.png

CPOE reflects how much more accurate a QB is compared to the modeled completion percentage (expected) based on player tracking data from thousands of plays in prior seasons. So he's tops of the EPA/play since he became a starter and he's above average in accuracy based on how difficult the throws he's made are.
 

houjix

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I haven't ever gotten deep into football "sabermetrics" but I assumed there would be a good way to evaluate an overall QB performance. Your comments just goes further to my point. Purdy has performed at a high level so far this season, and one down game against a top defense shouldn't all of the sudden change him to a glorified backup, especially when compared to other QBs in the league.
Yes and no. On a per play basis, yes, he has done well, but sometimes he isn't always asked to do a lot, so his total EPA is lower. He's had 5 ok-ish games, 2 pretty good games, and 1 amazing game from the perspective of how much he contributed to the win. Frankly, most coaches would be happy with that, especially if you have a strong run game and an elite defense.
 

BWRhasnoAC

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Purdy didn't have gaudy stats, but he did he one very important stat. 0 INT. He also made the throws in the most important moments and gave SF the lead. He played great. Don't listen to the talking heads.

Philly has really good defensive backs and a very good defense overall. This will be his hardest assignment yet. See if he can keep the dream alive.
 

burn587

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I’m not an advanced stats guy, and not saying they don’t have their place….but advanced stats somehow made the argument that Adam Dunn wasn’t a complete garbage heap of a baseball player.

QB play isn’t that hard to judge: complete a high percentage of passes, score TDs, don’t turn the ball over. Brock did two of these and won against an insanely good defense. The guy across from him getting paid 35 mil a year didn’t do that and he lost.
 
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wenkeej

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Yes and no. On a per play basis, yes, he has done well, but sometimes he isn't always asked to do a lot, so his total EPA is lower. He's had 5 ok-ish games, 2 pretty good games, and 1 amazing game from the perspective of how much he contributed to the win. Frankly, most coaches would be happy with that, especially if you have a strong run game and an elite defense.
Sometime I think we get too nit-picky, especially the closer we are to something. Is Purdy asked to throw 50 times and put up 350yds and 4 touchdowns per game to win, no. Does Purdy need to air it out 35 to 50 yds per throw to get big chunk plays, no. Is Purdy executing at a high enough level (can start to be nit-picky or subjective) for his team to continue to win, yes.
 

SaraV

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I was listening to the game tonight and John and Heft said the crowd went nuts when they showed one of the workers on the court wearing Purdy socks on the screen.
It was the ball boy. Timeout, he's on the floor with that circle mop near the Iowa State bench. Suddenly, on the scoreboard video, they zoom in on the kid's shoes and socks. At first I thought it had all of the basketball team faces, or maybe just one member of the men's team. Nope! Brock socks!
 

Rural

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I haven't ever gotten deep into football "sabermetrics" but I assumed there would be a good way to evaluate an overall QB performance. Your comments just goes further to my point. Purdy has performed at a high level so far this season, and one down game against a top defense shouldn't all of the sudden change him to a glorified backup, especially when compared to other QBs in the league.

Is it really down if you win?
 

Die4Cy

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Is it really down if you win?

Yeah, this is what I'm wondering also. The state of commentary is broken if you win a playoff game against the #1 defense to remain undefeated and they can't acknowledge it was done in a style that every other qb has to win with from time to time.

Talking heads now seem to want to apply special rules to Purdy's success.
 
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