A New Way to See Why Jacob Misiorowski's Fastball Dominates Hitters

At this point, most of the baseball world knows Jacob Misiorowski has one of baseball’s best fastballs. According to Statcast, Misiorowski’s heater ranks third among qualified four-seamers in pitcher run value (+12), first in whiff rate (42.5%), and 14th in expected slugging against (.262).

Those following the game closely probably also know what makes that fastball so tough to hit. In addition to averaging 100 and touching 104 MPH with it, Misiorowski’s 7.5 feet of extension down the mound adds an extra 2 MPH of perceived velocity by reducing a hitter’s reaction time, and he generates more carry on the ball from backspin than one expects to see from his low arm slot. In the 365 days since his major-league debut, Misiorowski has thrown 741 pitches with a perceived velocity of 102 MPH or higher, which is more than all but one pitcher—Aroldis Chapman, who's been pitching in the majors continuously since Misiorowski was eight years old—has in the pitch-tracking era. That abnormal combination of timing and angles often makes it nearly impossible to get on top of his fastball.

Thanks to Statcast’s new swing timing metrics, we can confirm how Misiorowski’s fastball misses bats, rather than inferring it from the eye test and hitter testimonies. For the most part, that original conclusion was correct. Hitters are later on his fastball than the MLB average (the middle bell curves), and they swing underneath it more than average (the rightmost bell curves). Look more closely, though, and there are more details about how much each attribute of Misiorowski’s fastball leads to those imprecise swings.

In the graphic above, the timing and vertical position of the swing are shown separately, but in reality, they’re closely related. Being late on a four-seamer typically makes a hitter more likely to swing underneath it. Every hitter’s bat path starts by traveling downward, at least slightly. If he starts his swing late on an elevated fastball, his hands and bat will probably still be traveling downward as his bat comes through the hitting zone, so he’ll swing farther underneath the ball.

But against Misiorowski’s fastball, that relationship between timing and bat path isn’t perfectly proportional, particularly compared to most pitchers. Hitters are late on 35% of swings against it, which ranks 41st among qualified four-seamers, but they’re underneath it on 63% of swings, which ranks 7th. Put another way, Misiorowski’s fastball gets no more late swings than Kyle Harrison’s, but it gets swings underneath it an additional 4% of the time.

That means that abnormal carry from a low slot—15.6 inches of induced vertical break from a 5.26-foot release height—might be most responsible for Misiorowski’s dominance, even if he gets more attention for lighting up the radar gun. That’s good news, because a pitcher’s excellence is more sustainable when it’s not tied strictly to velocity. Sitting in the triple digits takes Misiorowski’s fastball to another level, but it can still get bad swings underneath the ball at 97 mph. It’s not just a good pitch because he throws hard.

Misioroswki’s unicorn fastball also elevates his other pitches, particularly his curveball. When a hitter takes a bad swing at a breaking ball, he’s usually early. That’s the pitcher’s goal. It’s a slower pitch than a fastball, so it’s meant to catch guys out in front when they’re on time for a heater. Then there’s Misiorowski, who doesn’t get many early swings on his curveball compared to the average pitcher. Instead, 19% of swings against it are late, the highest rate among qualified curveballs.

Once again, a big reason for this is that Misiorowski throws hard. His curveball averages 87.4 MPH, the fifth-fastest qualified curveball in the game. But like his fastball, there’s much more to it than just velocity.

Misiorowski’s fastball is so good that hitters must devote their full energy to squaring it up. That means eliminating his slowest pitch. If a pitch starts around the zone, they’ll see it as a fastball, and beating the fastball—getting on top of it when it’s in the zone, and laying off when it’s not—is the top priority. If a pitch starts closer to the knees, they’ll often assume it’s a curveball and let it go for a ball, trying to stay on the fastball. That’s the right approach, as most of Misiorowski’s in-zone pitches are four-seamers, cutters, and sliders.

Unsurprisingly, opponents are swinging slightly more at Misiorowski’s hard stuff this year, but far less at his curveball.

When Misiorowski does plant an in-zone curveball, their pitch recognition short-circuits, prompting most of those late swings. Here’s Roman Anthony taking a very late cut at a comeback curveball.

Here’s Pete Crow-Armstrong making a late decision and getting tied up by a back-foot breaker.

In the same game, Seiya Suzuki managed to single it through the right side, but only via an 81.3-mph roller on an emergency swing.

For another non-whiff, here’s Jazz Chisholm Jr. realizing too late that he’s seeing a curveball down the middle, not an elevated two-strike fastball, and chopping it into the ground with a late, all-arms swing.

Swings on in-zone curveballs are often bad news for pitchers. Across the league, they’ve allowed a .348 xwOBA and -25 pitcher run value on such swings. In many cases, the hitter ambushed a hanger. Misiorowski, meanwhile, has allowed just a .213 xwOBA on in-zone curveball swings with a +1 run value, meaning it’s actually been an effective pitch for him. It all stems from establishing his elite fastball.

It was exactly one year ago that Misiorowski made his MLB debut. There were some early bumps in the road, but he matured into one of baseball’s best starting pitchers remarkably quickly. He’s gotten plenty of complimentary coverage in that time, and yet, there’s somehow still more about his performance to admire than meets the eye.