Let’s Fix Ross Stripling

The Blue Jays capped off a very busy 2020 trade deadline yesterday with the acquisition of Ross Stripling from the Dodgers. The NL West is probably the division I follow least closely, so I’m curious how Stripling’s year has been going. His 5.61 ERA isn’t good, but surely that’s a case of bad luck in a small sample and he’s primed to return to form. Let’s check out his Baseball Savant page to see how he’s doing.

Huh. That’s mostly very, very bad. Dodger blue is a sharp colour, but you don’t want that much of it on your stats page. I remember him being a pretty solid player, though, so let’s compare with his 2019:

That’s vastly different. He had a tendency to give up hard contact, although not nearly as often as this year, but he managed an above average strikeout rate while doing a decent job avoiding barrels (line drives and low fly balls hit over 95mph that almost always go for extra bases). His 2018 and 2017 numbers are even better.

My first thought here is “great, we’ve bought into the guy just as he’s turned 30 and his arm is going.” Looking a little closer, though, that explanation doesn’t hold up. The one number that moved significantly in the right direction is his fastball velocity, which went from the 16th to the 38th percentile. If his arm is shot, why is he throwing harder?

It’s not that he’s lost any movement either. His four seamer is getting two inches more rise and an inch more horizontal break than it did last year, and his slider and curveball are both dropping more than they did in 2019 (by 7 and 2 inches) without losing much or any horizontal movement. The only pitch that’s not moving more than it did last year is his changeup, which has more horizontal tail but about six inches less drop. Overall, it sure looks like his stuff is actually significantly better this year than it has been since at least 2017, when he was working almost exclusively out of the bullpen.

If it’s not the stuff, it must be the control, right? This one’s trickier to judge, but it doesn’t really seem to work as an explanation either. He’s getting a strike with the first pitch of a plat appearance 65% of the time, which is down a couple points from his career average but is still solidly better than the long term MLB average of around 61%. First strike percentage is a handy metric for basic control because we can assume pitchers are usually looking to get ahead to start off the PA. Robbie Ray, Stripling’s new teammate and a guy who has most definitely lost his feel for the zone, has started only 46% of hitters off with a strike this year, down about 13% from where he usually sits.

Stripling can throw a strike when he wants to, but maybe he’s not throwing quality strikes anymore. To help assess whether pitchers are putting the ball where they want in a little more detail, Baseball Savant divides pitches into four regions. The heart of the zone is what it sounds like, and broadly speaking isn’t where you want to put the ball. The shadow is the area just inside or just outside the zone. This is a good place to be most of the time, where you’re likely to get swings or called strikes but pitches aren’t quite as easy for hitters to square up. The chase zone is further out, and it’s where you want to throw when you’re ahead in the count and looking for a strikeout. The waste zone includes any place far enough from the zone that hitters aren’t at all likely to bite. In 2019, Stripling threw pitches in the heart, shadow, chase, and waste zones 26%, 44%, 22%, and 9% of the time, respectively. Those are all within a point of league average. In 2020, those percentages are 31%, 44%, 21%, and 4%. So he’s throwing a few more meatballs, which isn’t ideal, but it’s also not an extreme change, and it’s counterbalanced by fewer big misses. This doesn’t seem big enough to justify the implosion of his stats this year.

Nothing about Stripling’s profile as a pitcher seems to justify what’s happened, but maybe the way hitters react to him will tell us something. Hitters are swinging at fewer of his pitches this year, 43% vs 46% last year. They’re swinging a little less often inside the zone (61% vs 63%) but outside the zone they’ve gone from chasing 29% of the time (which is about average) to 21%. For some reason, he’s fooling hitters into chasing balls almost a third less often. Breaking it down by pitch type, his two breaking balls have gone from getting chases 30% of the time to 18% for the slider and 10% from the curve. Inside the zone, hitters are also swinging less at the curve, but more at the fastball and the slider.

In addition to hitters’ decisions of whether to swing, we can look at what happens when they do pull the trigger. Last year, hitters missed when they swung at Stripling’s change and curveball almost exactly a third of the time. His fastball and slider got whiffs 17% and 20% of the time, respectively. This year, the changeup, slider and fastball are all beating hitters a little bit less often (29%, 17%, and 14%, each down about 3%), but his curve has completely stopped challenging anyone, with a whiff rate of just 7%.

There’s his problem. Stripling’s curveball is his best pitch, the one he uses to put hitters away. All of the sudden, hitters aren’t offering at it, or aren’t missing when they do. They’re teeing off on it, in fact, with an average exit velocity of almost 94mph and an expected slugging percentage of .528. Last year, when they did hit it, hitters managed only a .278 expected slugging percentage on the pitch. His fastball is also getting hit hard, with an average exit velocity of nearly 93mph.

Why is this happening? It seems like Stripling has changed his delivery somewhat, and that as a result he’s basically tipping his curveball. The plot below shows Stripling’s release points in 2019 and this year. The plots on the left hand side are from the batter’s perspective, so vertical is height above the ground and horizontal is distance from the center of the rubber. On the left, the plots are from the first base line, so horizontal right is farther from the plate and left is closer.

You can see right away that there’s been a change. His 2020 release is higher by three or four inches, and about nine inches closer to the centre of the rubber. As well, his curveball is more distinct from the hitter point of view. In 2019, you can see that the blue dots (curveballs) blend somewhat with the green dots (fastballs) horizontally and vertically. In 2020, the curveballs come out distinctly higher without much overlap between that pitch and the other three. From the third base line side, you can see that he now gets more extension on the curve. He used to release it almost a foot further from the hitter than the fastball, but now it’s pretty close to the same.

This change hasn’t ruined she shape of the pitch. If anything, it moves a bit more than it did before. It does seem to have made it easier to see, though. That makes it easier for hitters to decide when to swing, watching good curves go by and swinging only at ones that are hung in the zone. It also explains why his other three pitches are getting fewer swings and misses. If you can rule out the curve on a given pitch, your odds of guessing right among the other three are better. From Stripling’s perspective, when your best pitch is suddenly easy for hitters to avoid, your whole arsenal is going to suffer.

So there, we’ve got a pretty solid theory as to what’s wring with Ross Stripling. Whether it can be fixed is a different question. In the short term, it might be hard to adapt his delivery on the fly to go back to how he did it in previous seasons. We’ve seen cases before of both pitchers and hitters making an off season change that didn’t work, then being unable to adjust back on the fly during the season. In the long run, though, if Stripling was able to change his delivery one way, he should probably be able to reverse that change when given time to work on it. It’s reassuring that his stuff and command appear largely intact. Pete Walker will have his work cut out for him, but there’s reason to believe that the prize of the Jays’ busy deadline can return to being the very effective pitcher he was for the past three years.