Was Joey Bosa right about Derek Carr?

“We knew once we hit him a few times, he really gets shook. And you saw on [Christian Covington’s] sack he was pretty much curling into a ball before we even got back there. So, great dude, great player. He’s been having a great year, but we knew once we get pressure on him, he kind of shuts down and he’s not as effective with a crowded pocket, so that was the key to it.”

Joey Bosa, after the Chargers victory over the Raiders

These words fired up Raider nation, including the team itself. Carr responded, “Maybe he was just trying to get under my skin. Which, he did piss me off. So, good job for that. But that’s not a bad thing, either.” Raiders fans seems to say something along the lines of “Well yeah duh. Every QB gets worse under pressure. Carr is one of them”

But is there some truth to what Bosa said? I’m going to test that here but first I need to formalize and paraphrase Bosa what said into two testable hypotheses:

1. In games that Carr is under lots of pressure his under pressure play is worse than in games that he is under less pressure. Essentially the more pressure, the worse he responds to that pressure.
2. If true, it is more true of Carr than it is of other QBs.

Let’s dive into the data to see if these are true.

In games that Carr is under lots of pressure, is his under pressure play is worse than in games that he is under less pressure?

All the data here comes from PFF. I’ve split up Carr’s game-by-game data into quartiles based on % of plays under pressure. I’ll refer to the bottom quartile as low pressure games (LPGs) and the top quartile as high pressure games (HPGs). To put this in real terms, LPGs are ones which he is under pressure less than 23.5% of dropbacks and HPGs are ones where he is under pressure 34.9% of dropbacks.

So in those games how does he do under pressure in these games? We can see here that Carr’s under pressure grade really does drop in these HPGs. The more pressured dropbacks there are in a game, the worse he gets in those pressured dropbacks. Its as if the heightened rate of pressure causes him to sensitize to pressure.

Note that error bars represent standard error

If true, it is more true of Carr than it is of other QBs?

Next I basically did the same analysis for the rest of the league (min. 40 games played). For each QB, I determined thresholds for LPGs and HPGs and then determined their mean pressure grade in each game type. Then, I aggregated all of those QBs and determined mean performance. Across the league there was not an appreciable difference in pressure grades in these two situations.

Note that error bars represent standard error

There’s probably a lot of noise here, however, and so to clean it up I reduced each QB’s data to a single metric which I’m calling pressure sensitivity index (PSI… get it?). Its a QB’s pressure average pressure grade in LPG minus HPG. Roughly speaking, negative PSI means they sensitize to pressure, a positive PSI means that they acclimate or desensitize to pressure. Across the league, the average PSI is -1.36 meaning ever so slightly sensitized to pressure. In contrast, Carr’s PSI is -9.75.

To better put this in context, I’ve provided a list of the 73 QBs who hit that 40 game minimum. Carr ranks 5th here, so he’s among the guys most sensitive to HPGs. That said, its not like we see good QBs at one end and bad ones at the other. Bosa even emphasized that Carr is a good player. He just sensitizes to pressure more than other QBs.

tl;dr – It may piss Carr off but there is some truth to what Bosa said. The numbers shows that in games where Carr is under pressure a lot his under pressure performance is worse than games in which he is mostly kept clean. This is true for Carr more so than most other QBs. That’s no disrespect. It’s a fact. 

I have two theories about the origins of Carr’s sensitivity to pressure: Theory #1. Maybe he’s born with it. Theory #2. Maybe its Maybelline.