It's hard to start an MLB career much better than Jacob Misiorowski has. The 23-year-old has allowed just two runs on three hits in his first 16 innings, while striking out 19 and walking seven. He was the first pitcher in the last 125 years to start his career with 11 hitless innings, and he outdueled the reigning NL Rookie of the Year, Paul Skenes, in a marquee matchup last week.
It would be understandable if Misiorowski was excited by his accomplishments, but the Brewers' rookie has maintained a level-headed approach through his early success.
"I think the biggest thing is not going on Instagram, not looking at all that stuff," he explained in the visiting clubhouse at Citi Field before a game against the Mets. "I mean, you're gonna see it, but I think that's the biggest part of [keeping focused], staying off of that stuff, and being able to be with family, friends, and my girlfriend, being around her. That's been huge that they've been with me."
In addition to having his family on the road with him during the early stages of his MLB career, Misirowski has found comfort in trying to live in the moment and take things one day at a time. "Through my whole career, I've been told, 'Hey, keep going. Stay where your feet are. I think that's the biggest thing with being able to stay mentally in control of myself, and just not thinking too far in the future."
The ability to control the mental aspects of his career may have come more easily to Misiorowski than controlling his impressive arsenal of pitches.
Coming into the 2025 season, he hadn't posted a BB/9 innings under 5.09 in either of his professional seasons and even posted a 5.32 BB/9 at Crowder College before even being drafted. He had never posted a walk rate lower than 11.9% at any stop in his minor league career, which led many scouting services, including MLB Pipeline, to question the 6'7" Misiorowski's ability to consistently repeat his delivery with his long limbs. A handful of those sites believed he was "headed for a high-leverage bullpen role as a right-handed Josh Hader."
However, Misiorowski began to rewrite the narrative early this season, showing clear signs of improvement in his command. In 63.1 innings at Triple-A before his call-up, he posted a 12.3% walk rate, which was his lowest at any level since 23 innings in High-A back in 2023. While those numbers aren't eye-popping, they're signs of growth for a young pitcher, and Misiorowski issued three walks or fewer in seven of his last nine starts in Triple-A. Over that stretch, he walked 22 and struck out 56 in 43.2 innings, that's a BB/9 of 4.2, which is a tremendous improvement from what we saw from him in 2024.
"I don't think it's been any one thing," he answered when asked what the cause of his progress was. "I think it's just been the work I put in over the years. I think it finally just clicked for me."
Some of the work that Misiorowski is referring to are specific drills he's done in his bullpens to ensure that his mechanics remain consistent and that he drives off the mound towards home plate, which can often be harder for taller pitchers with longer limbs that can throw off their center of gravity during a windup.
"The biggest thing for me is the water bags and staying on a good routine of throwing pens," explained Misiorowski. "I feel like if I do that every day, stay on that schedule, I'll be fine."
The use of water bags is a popular training method that many pitchers like Paul Skenes use andis explained in detail in this video from Tread Athletics. The water bag, which is worn on a pitcher's shoulders, creates dynamic resistance during a bullpen session, which forces the pitcher to create and repeat a more fluid and stable motion that can increase power and command through repeatable mechanics.
Misiorowski has found the water bags particularly helpful because they "make [his] front side feel more in sync and like locked up, so [he] feels like [he] hits that front side and [he doesn't] fall over or drift to the glove side, so it feels good."
Those repeatable mechanics and bullpen drills have been useful for the young right-hander this season, but they're not the only thing that has fueled his successful season.
"Also, using my eyes to throw instead of just trusting that the ball was gonna go somewhere," Misiorowski continued. "Maybe changing the sights a little bit, that's been a huge help."
That part about using his "eyes" to throw is a crucial step in the development of a young pitcher.
Misiorowski has as dynamic an arsenal of pitches as you will find. His four-seam fastball has posted a 133 Stuff+ grade, where a grade of 100 implies a league average pitch. His curveball also has a 143 grade, and his slider has a 117 mark. That's three pitches that are well above league average when it comes to raw stuff, and all three pitches have delivered so far this season. The fastball and curve are both in the 75th percentile or better in swinging strike rate, while the fastball is also 100th percentile in Ideal Contact Rate (ICR) allowed, and the slider has impeccable command with a 92nd percentile zone rate and 81st percentile strike rate.
When you have a mix of pitches with such an impressive combination of movement and velocity, it's easy to fall back on just "trusting your stuff." What's the harm in trusting a four-seam fastball that averages 99.6 mph and has a 14.5% swinging strike rate? Why not simply trust an 87.6 mph curveball that has more vertical drop at that speed than any other curve in baseball?
The reason is that simply rearing back and "just trusting that the ball was gonna go somewhere" can lead to pitches that are too imprecise. Maybe a fastball catches too much of the heart of the plate, or a curve doesn't start high enough in the zone to draw a swing. As Misiorowski advanced up the levels in the minor leagues, he needed to learn to lock in on his cues and find his sightlines or targets to ensure his pitches were as competitive as they needed to be.
"Everyone has their special [visual cues] or their thoughts that they have with a curveball, a slider, different things like that...You figure out what that is for you, and you do it like, repeat and repeat again," he explained. "The slider, for me, would be aiming at the catcher's elbow with the glove...The curveball I'm aiming at the umpire's face mask and getting it to drop in. And, you know, you're moving that sight down and up, wherever you need it. If you need it in the dirt, you're going like, bottom of the catcher's chin, stuff like that."
Establishing those visual cues and being able to adjust them based on what he specifically wants out of each pitch has been a huge turning point in Misiorowski's maturity on the mound. It has allowed each of his pitches to be more impactful and be thrown with a purpose. However, command comes and goes in the course of a given start for every pitcher. Leaning on your visual cues is an important component in re-establishing your command before the game gets away from you, but sometimes the in-game check needs to be mechanical. Misiorowski has locked in on that for himself this year as well.
"For me, I think the biggest [check] is the slider," he revealed. "The slider gets me back pretty good. I think it's just one of those things. That's the one pitch I've always had control over, so I think that's the biggest cue, just like, 'Okay, get back on the front side, feel good with the slider, and then the heater will follow.'"
Misiorowski's use of the slider to correct any mechanical issues makes complete sense. The pitch, which is 94.5 mph but features only 2.6 inches of horizontal movement, is one that he pounds the zone with against both righties and lefties. He's in the 92nd percentile in zone rate and 81st percentile in strike rate against hitters of both handedness. He also uses it early in the count 60% of the time or higher against both righties and lefties, posting a 90th percentile early called strike rate overall.
Even though Misiorowski's slider has an above-average PutAway Rate, which measures how often a two-strike pitch ends in a strikeout, against both righties and lefties, its value to him is not only in getting ahead in the count but also in keeping his mechanics and focus in check. Once he's ahead in the count, he can go to his four-seamer or curveball for swings-and-misses.
He uses his four-seamer 40% of the time in two-strike counts to righties, posting an 81st percentile chase rate in those counts, even though he has just an average PutAway rate. Against lefties, he uses his curveball 69% of the time in two-strike counts, and it has been a solid offering for him with an above-average 18.2% PutAway Rate and 12.5% SwStr%. The success of the curve and the fact that his fastball misses more bats against lefties has meant that Misiorowski has had better luck getting strikeouts against lefties than righties, but his strikeout potential is elite regardless.
That swing-and-miss upside was never in question with Misiorowski. He seemed like an elite reliever in a worst-case scenario. However, taking control of the mental elements of pitching and being a professional baseball player has allowed the 6'7" righty to improve his command on the mound and make the most of his tremendous upside. With his level-headed approach and support system, this feels more like a sign of things to come than a flukey small sample hot streak.
