The Many Fastballs of Jacob Misiorowski

Jacob Misiorowski didn’t just flummox the Cardinals. Sure, when the 23-year-old right-hander made his big league debut in front of 26,687 very pumped Milwaukee fans last Thursday night, he confounded the St. Louis lineup until a leg cramp and a lightly rolled ankle ended his evening after five no-hit innings. But he also baffled Statcast. “Sinker,” read the graphic at the bottom of the screen when Misiorowski rocketed a 100-mph four-seamer into the bottom of the zone for the first pitch of the game. His changeup often went down as a sinker, his curveball went down as a cutter, and his slider was sometimes classified as a cutter and sometimes as a four-seamer.

The classifications were working perfectly by the end of the game, but even early on, you can’t really blame Statcast here. For one thing, it didn’t have a baseline expectation to work from because this was Misiorowski’s debut. For another, all of these pitches really did look like fastballs. I don’t just mean that in a jokey way. I mean it very, very literally. Nearly every pitch Misiorowski throws really does look like a fastball; I was planning on writing about it before I even learned about the Statcast side of things. “That’s how I throw,” he said after the game. “Every pitch is trying to throw 100%.”

Before we get get into the specifics, we should also stop and address the fact that although Misiorowski is known as the Miz, it’s not too late to change his nickname to Le Mis (or even Les Mis, if you don’t mind some light noun-pronoun disagreement). You have to admit that watching Misiorowski pouring in 103 mph fastballs with this as his warm-up music would send shivers of fear down the spines of opposing leadoff batters:

Look down, opposing batters. If you find yourself standing in the batter’s box, you may indeed be standing in your grave. Misiorowski’s secondaries have the exact same characteristics, the same velocity and movement profiles, of actual fastballs thrown in recent seasons by major league pitchers. It’s not just that he throws his slider so hard that it looks like a fastball. It’s that his slider moves exactly like the four-seam fastball that Garrett Richards threw 1,236 times in 2021.

On Thursday night, Misiorowski’s slider averaged 94.5 mph, with 7.6 inches of induced vertical break and an inch of horizontal break to his glove side. It’s what you might call a bullet slider. In 2021, Richards’ four-seamer averaged 94.3 mph, 8.6 inches of induced vertical break, and 1.3 inches of glove-side break. The two pitches had the exact same spin orientation and percentage of active spin. Tell me these aren’t the same exact pitch:

So when I say that Misiorowski’s slider could be a fastball, I’m not taking liberties. No wonder Statcast defaulted to a fastball. You could argue that it wasn’t even wrong. It was literally Richards’ 2021 fastball, and in that season, its velocity was well above average. That said, opponents slashed .309/.392/.487 against it, so hopefully it works better as a secondary offering.

Eric Longenhagen captured slow-motion video of Misiorowski’s mechanics and pitch grips. The slider really does come out of his hand like a slider. You can see his hand get around the baseball. But he also throws it hard, has a lot of natural rise, and imparts a lot of gyro spin. (At some point, we’ll also need to talk about the way Misiorowski’s head whack sends his hat bouncing around on his head.)

Misiorowski’s changeup isn’t in Eric’s video, but it looks even more like a fastball than the slider. On Thursday night, it averaged 91.5 mph, 8.5 inches of IVB, and 19.4 inches of arm-side run. According to Baseball Savant, 12 different pitchers have thrown a sinker that averaged within one inch or mile per hour of all three of those numbers. Twelve! Brad Peacock actually appeared on that list in both 2017 and 2019:

Over those two seasons, Peacock’s sinker was within three-tenths of a mile an hour, half an inch of IVB, and three-tenths of an inch of horizontal break of Misiorowski’s changeup. Not only that, but the sinker was a great pitch for Peacock! Opponents batted just .231 against it, and it ran a 55% groundball rate. Anyway, that excellent Peacock fastball is now Misiorowski’s changeup:

Last up, we have Misiorowski’s curveball. On Thursday night, it averaged 87.9 mph, 9.1 inches of induced drop, and 5.7 inches of glove-side movement, and, well, you’ve got me there. Nobody throws a fastball, or even a cut fastball, that drops and moves to the glove side that much. But I have to tell you, only three players have ever thrown a curveball with an average velocity that high: Joe Kelly at 89.4 mph in 2023, Louis Varland this season at 88.4, and Alex Lange in 2024 at 88.1. PitchingBot currently has a perfect 80 on Misiorowski’s curveball, and Stuff+ sees it as the fourth-best curve in the game. So whether or not you can convince anybody that it’s a cutter, it’s awfully fast and it looks awfully good.

Before I leave you, I should confess that, as you might expect when a young pitcher has major-league-debut adrenaline coursing through their veins, Misiorowski’s velocity was a bit higher than normal on Thursday night. “I felt amped up,” he told reporters, and all of his pitches were a tick harder on average than what he averaged at Triple-A before his call-up. But the truth is, I could have easily run the same exercise using his Triple-A numbers. Misiorowski has gas to spare. Even if his slider averaged just 93.3 mph, as it has across 156 tracked pitches in Triple-A this season, that would make it the fastest slider of the entire pitch tracking era. You could probably run this same exercise with Edward Cabrera’s changeup or the famous Jacob deGrom slider of old, but deGrom is credited with 318 career fastballs above 100 mph over his entire career. Between the minors and the majors, Misiorowski is already at 82 this year, and we’re barely a third of the way through the season.

So if you’re unlucky enough to look down and find yourself standing in the batter’s box against Le Mis, you should probably gear up for the fastball. Even if you’re wrong, you may be right.