No. 18 prospect Milbrandt heads to AFL after solid 2025 season

For parts of three seasons, right-hander Karson Milbrandt called High-A Beloit home.

Major Leaguers dream of that kind of stability. Highly regarded prospects, however, want to advance levels on the way to The Show.

Milbrandt, whom the Marlins signed over slot value as a third-round pick in the 2022 MLB Draft, forewent college ball at Vanderbilt University to begin a professional career.

As Gatorade’s 2022 Missouri High School Player of the Year, Milbrandt had all the projectability to soar through the system. Instead, inconsistency held back his upside. While newer faces moved up the prospect rankings, Milbrandt compiled a 4.71 ERA over his first 46 starts and remained with the Sky Carp from 2023-25.

“It's God's plan, not really my plan, but just having a plan of attack to go out there,” Milbrandt said. “If something doesn't go your way, just control what you can control. I'd say a little bit of everybody [helping me out]. I feel like I always had the pieces, I just hadn't put [it] together yet. And this year, I really put it together. And then the result was pretty good.”

Things finally clicked for the 21-year-old, ranked as the Marlins’ No. 18 prospect, in his third full professional season.

After beginning the season on the injured list with right elbow tendinitis, Milbrandt recorded a 3.26 ERA and a career-high 11.8 K/9 rate in 19 starts for Beloit en route to the organization’s High-A MVP award.

Among Midwest League pitchers with at least 19 starts, Milbrandt posted the fourth-lowest ERA and the fifth-lowest batting average against. His 101 strikeouts were tied for ninth most despite having at least 12 innings fewer than those in front of him.

On Sept. 3, Milbrandt finally received a promotion to Double-A Pensacola following back-to-back 10-strikeout performances at High-A. With the Blue Wahoos, he allowed just two runs over 10 2/3 innings across two starts.

“He probably had his best offseason from a physicality standpoint,” director of Minor League operations Hector Crespo said. “You guys have heard us talk about strength and conditioning being our foundation, and I think the way he prepared his body coming into spring this year was really the separating dynamic for him to be able to pitch over the course of a year as well.

“I think we always knew he had the stuff. It was just more so the consistency of it. So I think from a physicality standpoint, to start, and then [director of pitching] Bill [Hezel] and the pitching group really putting an emphasis on a plan of attack for him.”

Milbrandt, whose high-spin fastball sits at 92-95 mph and touches 99 mph, bolstered the rest of his arsenal. He added a gyro-type pitch to go along with a changeup, curveball and sweeper.

Although the Major League club didn’t implement the coach pitch-calling strategy until the final nine games of the season, the Marlins’ affiliates had been doing so all season. In the case of Milbrandt, it helped develop his secondary offerings. Throwing live batting practice instead of typical in-between-start bullpen sessions also helped, in Milbrandt’s eyes.

“For me, it was just kind of throwing the ball over the heart of the plate,” Milbrandt said. “When I threw the ball over the heart of the plate, I dominated. When I walked people, I didn't, so just getting the misses smaller, and then filling the zone up.”

Milbrandt’s breakout season isn’t done, as he is part of the Marlins’ presentation at the Arizona Fall League for the Mesa Solar Sox. In his AFL debut on Wednesday, he allowed three runs on four hits, including two homers, across 3 2/3 relief innings. Milbrandt struck out four and walked two in a 58-pitch outing.

Though his walk percentage dropped from 13 to 12.3 this season, Milbrandt knows it needs to lower more. Across the board, his numbers improved -- from WHIP to BABIP. Milbrandt wants to finish up the year by continuing to dominate.

“Karson's been probably one of the hotter pitchers in, really, the industry right now,” Crespo said last month. “It's been cool. I think we've always known Karson to be as talented as any pitcher we've had in the system. It was just more so the consistency of being in the zone. It's been cool to see him really take that initiative and really let his stuff play in his zone. And it's attributed to the success he's had.”