Jacob Misiorowski's Outlier Stuff Shined in Hitless Debut

After Triple-A opponents struggled to hit Jacob Misiorowski this year, big-league hitters have started 0-for-14 against him. The right-hander held the St. Louis Cardinals hitless over five innings on Thursday night before departing with right leg cramping that appears unlikely to impact his availability for his next start. He struck out five, but that may undersell the extent of swing-and-miss he flashed – 13 of 37 swings (35.1%) against Misiorowski were whiffs.

"It was impressive," Pat Murphy said. "He was impressive every way you look at it."

Misiorowski's electric stuff was hardly a secret in the prospect world as he ascended the minor-league ranks, but in his debut, he announced to his new opponents that his outlier arsenal is already unlike anything they are accustomed to seeing.

"His pitches are incredible," said Misiorowski's battery mate William Contreras, who guided him through a game plan that mixed those pitches a bit differently than he had in many of his minor-league starts.

His trademark velocity was there from the get-go, starting with a first-pitch fastball that clocked in at 100.5 mph. Misiorowski's four-seamer averaged 101.2 mph in his first inning and reached 102.2. That velocity gradually inched downward as his start progressed, but he reached back for triple digits again with his final pitch of the fifth inning.

"Me and (José) Quintana, we were sitting together trying to guess how fast the first pitch was going to be," Freddy Peralta said. "When we looked at it, we were like, 'Oh my God, it's going to be a long night for the hitters.'"

It's not just raw velocity that makes Misiorowski's heater elite. He slings it from a low-three-quarters slot but generates more backspin carry than most pitchers do from his 21-degree arm angle, averaging 16.7 inches of induced vertical break on Thursday. He also kept it up in the zone, which only adds to its rising effect. The result is a flavor of perceived movement unlike any other four-seamer at the MLB level.

Finally, Misiorowski's average extension of 7.5 feet down the mound also shortens the hitter's reaction time, with Statcast estimating that it adds 2 mph of perceived velocity to his pitches. Even when his fastball is "down" to 98 mph, it's still effectively a 100-mph heater. The combination of velocity, movement, entry angle, and extension creates a near-unprecedented pitch that multiple prospect publications scouted as an 80-grade fastball.

That fastball is good enough that Misiorowski will be able to dominate with his best pitch alone in some outings. However, he only threw it 52.6% of the time in his debut, the lowest rate of any of his starts this year. Meanwhile, 30.1% of his pitches were sliders, his other outlier pitch. It dismantled the Cardinals, generating whiffs on four of eight swings against it.

"Maybe a few more sliders than I usually (throw)," he said postgame. "It was working, so we rolled with it."

Misiorowski's slider averaged 94.5 mph and touched 96.4 on Thursday, which would make it far and away the fastest qualified slider in baseball. However, the way it spins and breaks out of his hand more closely resembles a cutter than a slider. Even if it's best classified as such, its velocity would still rank third overall and first among starters.

The dominance of multiple pitches stood out to those observing in the dugout and on the field.

"It wasn't just maintaining the velocity, it was his mix," Murphy said. "His (slider) was good. Breaking ball was good. Even threw a really good changeup to (Nolan) Gorman at one point."

"On my end, what I liked to see out of him was the different pitches he was able to throw and combine them together," said Contreras.

It was just one outing, and Misiorowski's four walks were a necessary reminder that inconsistent control will likely lead to peaks and valleys throughout his rookie season. Still, his inaugural showing confirmed that he can execute his unique stuff well enough to overpower big-league hitters right now. That's why he's here.

"It certainly bodes well," Murphy said. "We saw (Brandon Woodruff) debut, we've seen (Freddy) Peralta debut – he had a great one. We've seen Corbin Burnes debut, go up and down, and then really get on it. I think we probably have somebody in the same mold."