Have You Tried Turning Corbin Burnes Off, Then Turning Him Back On Again?

Corbin Burnes
John Hefti-USA TODAY Sports

The 2023 season represents a golden opportunity for the Brewers. Their long-time tormenters, the Cardinals, can’t get out of their own way. The Cubs aren’t quite ready for prime time yet. The Pirates are an awesome story, but they’re light on impact players; this feels more like a feel-good warmup for the future than their year to shine. But the Brewers have problems of their own: their vaunted starting pitching has let them down to start the year.

You might assume I’m talking about the shaky back of the rotation; after all, the Brewers have been built around Corbin Burnes, Brandon Woodruff, and Freddy Peralta for years now. But Wade Miley is holding up his end of the bargain, and even Colin Rea and Eric Lauer have turned in mid-4s ERAs — hardly a disaster. Instead, the problems have come at the very top: Woodruff is out indefinitely with a shoulder injury, and Burnes simply doesn’t look like himself this year.

Over the past three seasons, Burnes had established himself as one of the best pitchers in baseball. He has outrageous strikeout stuff; his 33.4% strikeout rate over those three years was 0.1 percentage points off of the best mark in baseball for a qualified starter. He mastered his command in the past two seasons, turning in back-to-back years of excellent walk rates. He even added durability, topping 200 innings in 2022, the first time in his career he’d even exceeded 170.

What’s gone wrong this year? A little bit of everything, to be honest. He’s walking more batters. His strikeouts have gone missing in action. His velocity is down across the board, as are his swinging-strike and chase rates. He’s giving up more contact than ever before, and “ever before” encompasses the 2019 season, when he ran up an 8.82 ERA and 6.09 FIP and got sent to the bullpen. In sum, he’s pitched to a 3.86 ERA and 4.34 FIP this year, quite the letdown after his last three years produced a 2.62 ERA and 2.40 FIP.

You might expect that whatever is wrong with Burnes starts with his cutter. It is, after all, his primary pitch; his big glow-up came when he stopped throwing a four-seamer and started leaning into his natural cut. But despite a slight dip in velocity, his cutter is putting up strikingly similar results to last year:

Cutter Results, ’22-’23
Year Zone% Swing% Contact% SwStr% pVal/100
2022 53.0% 47.9% 74.9% 12.0% 1.5
2023 56.4% 47.9% 75.3% 11.8% 2.4

It’s even moving similarly:

Cutter Shape, ’22-’23
Year Velo (mph) HMov (in) VMov (in) Total Mov Spin Rate Spin/MPH
2022 95.1 2.2 6.9 7.4 2626 27.6
2023 93.8 2.0 6.4 6.9 2605 27.8

You might look at these tables and think that I’m grasping at straws. It’s hard to say those pitches are different, and he’s still getting solid results. But I didn’t buy it, so I kept looking closer. Two things stand out after enough such staring. First, he’s altered his delivery very slightly. Here he is in 2022 throwing a middle-middle cutter for strike one:

Here he is in 2023 doing the same:

When he pulled his arm back last year, it got as low as his belt, an ultra-short motion. This year, he’s letting it go longer. Here are two stills frozen at roughly the same point in his delivery:

Maybe this is related and maybe it’s not, but Burnes’ fine command of the pitch has waned this year. Think of the strike zone as two regions: the heart, and the areas around the edges — pitcher’s pitches, in other words. This is a bad trend:

Cutter Location, ’21-’23
Year Heart% Edge%
2021 29.6% 24.9%
2022 27.1% 24.1%
2023 32.1% 19.4%

More pitches over the heart of the plate is one thing; maybe he’s just focusing more on throwing strikes, or aiming down the middle and letting the movement play. But it should come with more pitches on the edges, too: if you’re just hucking it middle-middle, lots of your misses will hit the corner. Fewer pitcher’s pitches and more pitches over the heart of the plate at the same time is a bad combination.

In ‘21 and ‘22, Burnes complemented that cutter with a hammer curve that posted absurd swinging-strike rates. In ‘23, the curve has gone haywire:

Curve Results, ’22-’23
Year Zone% Swing% Contact% SwStr% pVal/100
2022 34.9% 42.6% 53.9% 19.6% 1.1
2023 33.0% 34.0% 62.9% 12.6% 0.4

This one is particularly baffling, because he’s added downward movement to the pitch. Indeed, stuff models think it’s about as good as ever. What’s wrong? Again, it’s the location:

Curve Location, ’21-’23
Year Heart% Edge% Waste%
2021 19.0% 19.8% 15.6%
2022 15.8% 19.2% 16.6%
2023 21.4% 10.7% 17.5%

He’s almost never hitting the corners anymore; heck, he’s throwing the curveball in the Baseball Savant-defined shadow zone, the corners plus the area just off the plate, only 29% of the time this year, down from 38% over the past two years combined. More pitches dead red and fewer in tough locations for hitters to handle is a bad combination. He’s not even saving wasted pitches by attacking the middle of the plate; his rate of wasted curveballs is higher than ever.

The story is more complicated with his slider. He’s locating it roughly as well as he has over the past few years; the pitch has always been more about raw stuff than location. This year, though, batters aren’t flailing at it like they used to. Take a look at the contact and swinging-strike rates for his slider over the past three years:

Slider Results, ’21-’23
Year Zone% Swing% Contact% SwStr% pVal/100
2021 40.8% 57.6% 54.0% 26.5% 3.0
2022 30.8% 49.7% 52.0% 23.8% 1.2
2023 26.8% 53.6% 76.7% 12.5% -1.0

Could it be as simple as the fact that Burnes is throwing it more slowly than before without getting more movement? Our two pitch models think the pitch is meaningfully worse than it was in the last two years, so that’s certainly an option, but let’s not overlook sample size. Opponents have swung at exactly 30 Burnes sliders this year. Maybe they’re just on a hot streak, or maybe variance is just biting the slider at the wrong time. I have my eye on that as a potential explanation, but make no mistake: the pitch just isn’t fooling hitters like it used to. Opponents have swung at 13 sliders in the strike zone and made contact with all of them, though one was a foul tip. That’s a depressing statistic for a pitch that was nearly unhittable in recent years.

It probably won’t surprise you to learn that Burnes’ longer delivery shows up on his curveball and slider, not just his cutter. That’s for the best, because it makes his pitches harder to distinguish, but I can’t shake the feeling that all of this is connected. He’s throwing everything more slowly, and his command is in a funk. The margins are thin in the big leagues. Miss your spots, and you’re fighting uphill, no matter how nasty your stuff is.

One of my favorite silly statistics does a great job of explaining how important hitting the edges of the zone is. The best pitcher in baseball last year was Emmanuel Clase, and I don’t think it was particularly close. He allowed a .167/.200/.225 line to opposing hitters, good for a .187 wOBA. I can’t give you a full-season hitter comparison for how putrid that is because it’s worse than anyone ever is. It’s worse than Jeff Mathis‘ career line. David Hensley is hitting .129/.229/.145 this year, and that is a .187 wOBA. It’s bad — like, really bad.

Clase’s pitches saved 2.2 runs relative to average for every 100 pitches he threw. That’s outstanding; again, did you see that batting line he allowed? Cy Young winners Justin Verlander and Sandy Alcantara checked in at 1.6 runs and 1.2 runs per 100 pitches, respectively. That should give you an idea of the proper scale for runs saved per 100 pitches. All pitches thrown in the shadow zone — every single one, from ones thrown by the greats to ones thrown by position players pitching — saved 1.7 runs per 100 pitches. Throw it on the borders, and you’re great.

Burnes has never been an excessively fine pitcher, but he located his pitches in the shadow zone a league-average amount over the past two years. This year, he’s hitting it three percentage points less frequently than average. That means more middle-middle pitches batters are looking for, and more pitches that aren’t close enough to entice a swing. It’s a cascade of little failures that’s adding up to a big one; Burnes hasn’t looked this hittable, this human, since 2019.

What is there to do about it? I’m partial to my titular suggestion: turn Burnes off, wait ten seconds, and then turn him on again. It works for my router. I don’t condone violence, but I’ll also note that sometimes I give it one well-placed whack when it’s acting up; perhaps the Brewers could ask Burnes to do that himself. He just seems ever so slightly off, in need of a reset. It couldn’t have happened at a worse time, either: 2023 should be their year in the NL Central. They just need Burnes to lead the way.

Ben is a writer at FanGraphs. He can be found on Twitter @_Ben_Clemens.

Newest Most Voted
Inline Feedbacks
View all comments
11 months ago

Nobody knows his kinks, which is probably the only reason Brewers fans haven’t tried.

I mean, what?

Anyway, the biggest problem I can see with his delivery isn’t actually the extended load, it’s the fact that his arm position as he brings it up is completely out of whack and out of sync with the rest of his body. He looks almost like his upper half pushing itself through the pitching motion faster; his stride doesn’t have time to transfer the full strength of his landing into his arm motion. That might be due to injury, but honestly, that seems more likely to cause injury than be caused by it. Very interesting analysis, but unless his pitching motion is out of sync on the rest of his pitches, I don’t think that’s a primary cause.

11 months ago
Reply to  EonADS

Yeah it looks like he used to keep his weight back better up until landing, allowing him to keep his arm in sync and generate more velocity on his pitches. Could be a lack of lower half mobility caused by some injury. Maybe he lengthened the arm action to compensate for the lower half issues generating velocity, but that arm action is definitely the clearest sign that he made a deliberate change. You have to wonder why.

Thanks for coming to our armchair pitching coach lesson.

11 months ago
Reply to  viceroy

You might be on to something with the lower body injury; at a second look, it almost seems like he’s trying to keep his weight off his plant foot as long as possible. That could explain the lagging arm motion as well; attempting to compensate for the drop in sheer force he can generate without a firm step.

11 months ago
Reply to  EonADS

To me his whole delivery just seems way more high-effort than it was last year. Whether he’s compensating for injury or velocity loss or whatever is causing it, I’m not surprised at all that the guy with the delivery in the first gif has better command than the guy with the delivery in the second gif.