Corbin’s Hammer

Corbin Burnes is laying waste to the National League, putting up numbers that can best be described as comical. A 34.6% strikeout rate? That’s closer territory. A 4.8% walk rate? That’s lower than Kyle Hendricks’ career mark. His 2.27 ERA might undersell how good he’s been; both his xERA (a Statcast ERA estimator) and FIP are in the ones (1.96 and 1.58, respectively).

You know about the cutter he leads with, which he described to David Laurila earlier this year. You know about the slider and sinker, the two pitches that complement his cutter. That trio took the league by storm last year, and he’s doubled down on cutters this year; he now throws the pitch roughly half the time.

Like an annoying hipster, though, I’ve moved on to the next cool Burnes thing that no one is talking about yet. The cutter? It’s fine, I guess (it’s the best cutter in baseball, but I’m doing a bit here, so bear with me). I’m here to talk to you about the curveball, a pitch that he threw less than 10% of the time before making it a staple this season.

If Burnes has one standout skill, it’s his ability to impart spin. Even when he was bad, he threw the highest-spinning four-seamer in the game, and his slider has always jumped out of his hand. It’s hardly a surprise that his curveball is cut from the same cloth. Spin data is fraught this year, what with the foreign substance crackdown and all, but since June 21, he’s thrown his curveball with a whopping 2,840 rpm, the 16th-best mark in the game (21st-best if you consider spin-to-velocity ratio instead).

What does that mean in English? It means that he has the raw stuff to generate eye-popping movement. He also throws the pitch in the low 80s, which means batters don’t have a ton of time to react. Put those two things together, and you can make MVP candidate Buster Posey look like a toddler learning how to walk:

The pitch is an absolute delight, and it’s also phenomenally effective. Batters have come up empty on half of their swings against it, the third-highest mark in the league (and 45% since June 21, so don’t go sticky-stuff-asterisking up this great pitch). As an added bonus, he’s seventh in baseball when it comes to batters not swinging at pitches in the zone. He throws it for a strike 49.3% of the time, which ranks seventh in the majors, and batters take it, doing his work for him. Can’t hit it when they swing at it, often take it when they should swing at it: what’s an opposing hitter to do but complain?

Why feature the curve over the slider? It’s all part of an increasingly batter-unfriendly pitch mix that forces hitters to guess what’s coming, leaving them susceptible to really bad swings — or really bad takes. Think of the cutter/slider/curveball spectrum as three variations on the same pitch. Per Baseball Savant, here’s how they break, as well as the speed they’re thrown at:

The three offerings he throws most often all break gloveside. They do so at different speeds, though, which results in different movement; the slower the pitch, the more it breaks in both planes. The difference in drop is more than the different speeds alone would suggest; the cutter’s spin makes it fight gravity, but the curveball goes with the flow and breaks downward.

That sounds like it would make things easy on the hitter; just look to one side and go from there. But these differences in velocity are huge, which means timing the right pitch and working out where it will cross the plate is difficult. Not only that, but the difference in horizontal movement means batters also have to ask themselves constantly where the ball will end up. You can’t just see glove-side break and assume it’s the curve or slider; his cutter is liable to hold the zone and leave you looking foolish:

A slider misses there. A curve misses by more. There’s not a lot of time to decide what’s coming, and with a base open, it’s hardly surprising that Tyler O’Neill guessed breaking ball.

By using the curve more, Burnes is giving the batter an even tougher decision. Before, he frequently paired cutters and sliders, and the velocity and movement gave batters some recourse: if they thought cutter and got a slider (or vice versa), the pitches were close enough that they stood at least a chance of making contact.

The curveball isn’t as objectively nasty as the slider. Burnes’ slider is absurd; it gets three inches of drop more than most thrown at its velocity, and it also gets 3.5 inches more horizontal break. Oh, and he throws it 88 mph and tops out above 90. Pitches that move that fast just don’t break like that, at least when anyone else throws them. It’s truly one of the best sliders in the game.

His curve isn’t quite as much of a standout; it has roughly average total movement, though it’s more two-plane than north-south, which gives it a slightly different look. But a 15-mph gap from his primary pitch is a difference maker; if you’re sitting on a cutter and instead swing at a curveball, there’s no coming back from that. That’s what made Posey look so silly up above, when he stood a decent chance of at least making contact with a slider.

It works in reverse, too. By making batters look for a low-80s, two-plane pitch, they stand little chance of getting to an unexpected cutter. It was hard to believe Burnes would improve on his cutter from last year; he had a career year in a short season. But he’s putting batters away more frequently with it this year, and missing bats just as frequently, despite throwing it twice as often. It’s speculation, but I think the curve has something to do with that.

He’s also a freaking surgeon with the pitch. For a guy who walked 8.8% of the batters he faced in the majors before this year (and 10% in his dominant 2020), Burnes sure seems to have great command. He either tucks the pitch into the lower corner or bounces it; batters simply don’t get much to hit:

You’d think that would limit his ability to play his pitches off of each other somewhat, as he generally locates the cutter on the opposite corner. But the bounced pitches look like cutters out of his hand, and the ones that dot the corner look like cutters that will stay off the plate; just because he doesn’t throw a ton of those doesn’t mean batters don’t have to respect them. His outside-corner cutter to lefties has been a weapon this year, which only makes that curveball location better. Good luck with that curveball when you’re also on the lookout for this:

In fact, by pitch values, Burnes’s curveball has been his best offering this year. That doesn’t mean it’s actually his best pitch; on a pure stuff basis, there’s a solid argument that it’s his fifth-best. But it’s a great lesson in contextual pitching. It’s incredibly valuable when he throws it because it pairs well with his most-thrown pitch, and it also pairs well with the slider. And having the three pitches in a spectrum means that even if a batter picks “not-cutter,” there are still two speeds of breaking ball to guess between. Similarly, figuring out “not-curveball” isn’t as helpful as you might think.

One more thing: the curve is a tremendous partner to Burnes’ changeup. They come out of his hand with roughly opposite spin and transverse spin percentage, which makes them hard to distinguish. But the changeup moves just a little differently:

He hasn’t thrown a single changeup to righties this year. Against lefties, he uses it in place of his slider, which gives batters a wholly different problem to solve.

It’s yet another bind for hitters, which is Burnes’ specialty these days. He has a seemingly endless array of plus pitches, and his newest weapon is helping unlock them all. Not bad for a curveball he’d used only sparingly before 2021.