The highly-touted flame-thrower had mowed through his first five innings, striking out five batters without allowing a single hit in the Milwaukee Brewers' 6-0 victory over the St. Louis Cardinals Thursday night at American Family Field.
But it came to an abrupt and premature end just three pitches into the sixth inning when Misiorowski's right calf and quad started to cramp up on him, drawing a visit from the Milwaukee Brewers' athletic training staff and ultimately closing the book on a debut for the ages.
“The kid was great,” Brewers manager Pat Murphy said after his team's 6-0 victory. “He was impressive, every way you look at it. He was nervous going into it, which is to be expected, but he handled it really well."
The Brewers have produced some impressive minor-league pitching prospects in recent years but none of them came with the firepower of Misiorowski, who's fastball regularly hits tripe digits on the radar gun and got as high as 103 MPH with Triple-A Nashville this season.
And sure enough, the first pitch he threw Thursday night was a 100 MPH fastball that sailed "right down Wisconsin Avenue," in the words of legendary late Brewers broadcaster Bob Uecker, past the bat of Cardinals second baseman Lars Nootbaar.
Misiorowski's next two pitches clocked in at 101.8 and 101.4 MPH, respectively, and after an 89.1 MPH curveball, he threw another fastball, this time at 102.2 MPH before getting Nootbar to ground out.
In all, 14 of Misiorowski's pitches reached at least 100 MPH -- six more than the combined total of all Brewers starters since pitch-tracking began in 2008.
"That's just how I throw," Misiorowski said.
The fastball, though, wasn't the only attraction Thursday night as Misiorowski also dipped into his arsenal of secondary pitches including a slider that reached 95 MPH along with an effective curveball as well as a couple of well-timed changeups, all of which contributed to 13 whiffs by Cardinals batters.
"It wasn't just maintaining velocity," Murphy said. "It was the mix."
The only blemish on Misiorowski's night was the unfortunate cramping issue.
After striking out the last two batters in a 1-2-3 fifth, Misiorowski was at 78 pitches for the day as he headed to the dugout where his break was extended when the Brewers' offense sprang to life with five runs against St. Louis right-hander Sonny Gray.
Despite the longer-than-usual layoff, Murphy and his coaching staff agreed to send Misiorowski back out for the sixth on a hitter-by-hitter basis but appeared to roll his ankle on his third pitch of the inning.
Misiorowski, though, was fine after the game and is already looking forward to taking the ball again five days from now.
So, too, is his manager.
"It certainly bodes well," Murphy said. "We saw (Brandon Woodruff's) debut. We saw (Freddy) Peralta's debut. We saw Corbin Burnes' debut and go up and down and then really get on it.
"We probably have somebody in the same mold."