Context Stats: Bryce Petty vs the 49ers

Statistics let us remove emotional stimuli and focus on the hard truth of what happens. But we need to place statistics into their environment to gain context and understand what’s really happening. Bryce Petty having 60% accuracy doesn’t tell you any information, but 60% accuracy throwing against man coverage gives you something to work with. That’s the purpose of this season-long project.

Let’s get this out of the way, these numbers aren’t objective. There’s a lot of subjectivity involved with interceptables, drops, single vs full reads, and even what the coverage faced is. This is still a subjective analysis. It’s just adding numbers to that subjective analysis.

So, Bryce Petty started off well.

It took a long collapse of one of the leagues most overrated players (yeah, even a player who isn’t good can be overrated) but finally, Petty got in. He didn’t start well at all, or play well altogether, but compared to the first start against the Rams it was a night and day difference. We got to see full Petty. We got to see who Bryce Petty is overall as a player right now.

The interception above isn’t worth dwelling on. It’s a thoughtless pass to Enunwa where the cornerback made a great play and Enunwa ran a bad route, turning before he was supposed to. Petty had no control over that interception, and the only thing he could do is rifle it harder- although that’s not really within his power. The pre-snap read is fine and this throw is made entirely off that read (off coverage against a short curl). So don’t overthink it.

Petty’s been given the moniker of “big arm” QB. It’s probably because he looks the part (6’4, 230) and he plays the part (he LOVES throwing deep) but his actual arm isn’t that strong. Generally, a strong arm is able to push the ball far at low arcs and at high velocity, Petty has consistently thrown high arcs with low velocity aka lobs. Petty’s regular velocity is actually slower than most NFL QBs.

Bryce Petty Context Stats - Combine
The actual science of determining Throw Velocity is imperfect, but the most current version of the equation would put Petty in the 22nd percentile, which is in the bottom quarter of the league.

The context stats aren’t kind to Petty again, especially after taking as many sacks as he did. But he actually looked like a better player in this game than ever before. It came against one of the leagues worst overall defenses; but at least it’s something.

Bryce Petty Context Stats - Reads

Petty shows a surprisingly good “Multi Field Read” number but that is also not entirely truthful. Petty’s full field reads came from improvisation after scrambling, instead of scanning the field like you’d want to see. Regardless, his ability to break plays and make things happen was actually really impressive at times.

So let’s break this into two parts: Good Petty and bad Petty.

On the first play, it’s five-wide with a weird cover-1/cover-2 man look. One safety is in his regular cover-2 spot but the other is extremely close to the wide receivers on the left. Petty is probably unable to figure out what exactly is going on with the defense, so he decides to immediately search for his checkdown to get what he can, which is a fine decision. When pressure comes in as he raises his arm to throw, he moves and then decides to climb up the pocket. However, because he keeps his eyes downfield he finds an open Bostick for a significantly bigger gain than the checkdown. He even makes a great throw on the move away from the defender.

The second play hints towards a cover-2 zone. After a poorly executed playaction, a defender forces Petty to leave the pocket again. Anderson, originally running a post, sees Petty scrambling and bends towards the sideline. Petty turns to set his feet, throws it up, and gives a very good opportunity for Anderson that comes down with it. I marked this pass as perfect, it’s a coverage beating throw. A really difficult one, at that.

The pre-snap starts off showing cover-2 man, but when the motion man comes into the slot and one corner is faced with covering two receivers, the likelihood of zone rises. Petty sees an opening that isn’t actually there at all, and that’s not a negative. It’s a compliment, this hole isn’t existent in anywhere but Petty’s mind and he finds it on the field and throws a perfect ball to the sideline for Marshall. Unfortunately, Marshall can’t come down in bounds but it’s very well thrown. Petty has to maximize his placement like this to cover for the velocity issues and when he does, it looks like this. It also looks like the second play.

The second play is pure touch. Petty has a potential blitz coming as defenders begin to shift along the left side of the line. When he snaps, the entire left side comes and Petty takes a second to look at it. Instead of playing by the rules and throwing into the overload, he checks the middle, sees the safety running into the middle, and turns and throws at Marshall. To me, this seems like a pre-determined pass but it doesn’t change that it’s thrown with great touch to land right into Marshall.

These are good plays. Not good plays in context of what we’ve seen from Jets QBs, these are actual good plays.

So what about the bad Petty? That can be split into two parts; first comes the stats:

Bryce Petty Context Stats - Pressured

I’ve split Pressured into two sections, one including sacks and one not including sacks. It’s obvious what i’m pointing out here. Petty can easily throw when pressured and make the throws count, but his reaction to pressure isn’t great. The tape all shows the same thing, bad blocking and a poor reaction to bad blocking. It’s not Petty’s fault that he’s getting pressured easily, but on some of the sacks he takes, it’s his fault the balls not out of his hands. Even throwing it into the stands is preferable, just get it out. Intentional grounding is better than trying find something.

Of course, the 3 interceptable passes on 31 non-pressured attempts are problematic. That’s once every 10 passes. Adding up his two starts this season, Petty’s averaging one interceptable every 18 attempts; which isn’t too bad. But his horrible 5.12 YPA has to improve if that’s the rate he’s going to throw them at.

Then there are these very unfavorable stats:

Bryce Petty Context Stats - Inaccurate

Petty’s inaccurate a lot. 26% of his non-screen passes were off target and require unnecessary adjustment. You can’t have a career where 26% of your passes border on uncatchable. Ryan Fitzpatrick was crucified this year for his horrific accuracy and he only had 18% of his passes given the inaccurate tag.


Here’s the second half of the bad Petty, the interceptables. As usual, if you can make a convincing case that one of these plays shouldn’t count as interceptable, i’ll remove it from the list and stats. Petty’s first intercepted pass (the one at the start of the article) isn’t in this section, because i didn’t count it as interceptable. There’s nothing Petty did wrong on the play as far as I can see. He even placed the ball as far away from the cornerback as possible, it’s just the corner making a good play off a badly run route.

Cover-2 look on the pre-snap against an empty set. It turns out to be zone. The post is a great choice against cover-2 because of the way the zones work out, but the linebacker gets in the way and the safety anticipates the route. Petty is throwing ahead of Enunwa and directly in trajectory of being caught by the safety, but an amazing stretch for the ball brings it back to Enunwa.

Following a pre-snap motion, the 49ers turn into a cover-1 man look. Petty, dropping back with his head focused in the middle, gets the safety to stay put in the center while he takes a deep throw at the sideline. Good thought but not a great time to do this. Anderson is not open at any point, and he barely knocks away this potential interception. There’s nothing mentally wrong about Petty’s choice on this play, given that Anderson is even with the CB when he lets the ball go and in most cases that would be a good sign he’s about to leave him behind. He just doesn’t this time and the ball ends up in position for the corner.

Another cover-2 look, this time with the solo receiver’s corner hinting man while the opposite side giving a zone look. Petty does another really poorly sold play action that still gets the deep safety on Enunwa’s side to bite. With the safety out of position, Petty takes the deep throw but its completely off. Petty gives the corner a chance to make this interception but they don’t take it.

Extra Stats

Bryce Petty Context Stats - Defense
Petty was anywhere between bad to underwhelming in all but when hit and movement off spot (where the QB is forced to leave or move around the pocket). His improvisation helped boost the latter. Although Petty has a very high YPA in 3rd and long, the low amount of conversions should help tell why; many of the 3rd and longs were chunk yardage that ultimately didn’t account for anything. He had six attempts on 3rd downs of 10 yards or over in this game, converting two.

I credited Bryce Petty with 2 passes in stride and 2 coverage beating passes in this game. He suffered only one drop for 17 yards for the game, on a perfect strike to Anderson.

Bryce Petty Context Stats - Passing Map
Petty was a lot more comfortable taking chances around the field this time around.

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