Looking nasty at Spring Breakout the latest step for rising prospect Milbrandt

WEST PALM BEACH, Fla. -- No Thomas White? No Robby Snelling? No problem.

Marlins No. 10 prospect Karson Milbrandt struck out six Astros prospects over three hitless innings in Thursday afternoon’s Spring Breakout game at CACTI Park of the Palm Beaches.

“They told me about two, three weeks ago that I [was] built up for three, that I'll be starting this,” Milbrandt said. “Some good, some bad. Obviously, three walks, not good, but six punchies is good. Still working on the feel stuff.”

In the third annual prospect showcase, the Marlins tabbed the right-hander to start following back-to-back years of White doing so. White, who ranks as MLB Pipeline’s No. 17 overall prospect, is rehabbing from a Grade 1 right oblique strain. Miami reassigned Snelling, MLB Pipeline’s No. 39 overall prospect, to Minor League camp on Wednesday after an impressive big league camp.

Milbrandt, who turns 22 on April 21, was more than worthy of filling in for that pair. After two forgettable seasons at High-A Beloit, the third time proved to be the charm for Milbrandt in a breakout 2025 to emerge as the organization’s latest top pitching prospect.

As the Sky Carp’s MVP, Milbrandt compiled a 3.26 ERA and a career-high 11.8 K/9 rate in 19 starts despite beginning the season on the injured list with right elbow tendinitis. Among Midwest League pitchers with at least 19 starts, he recorded the fourth-lowest ERA and the fifth-lowest batting average against. His 101 strikeouts were tied for ninth-most even though he pitched at least 12 innings fewer than those in front of him.

“We always talk about confidence comes with preparation, and he's just a different person,” director of player development Rachel Balkovec said. “He's more confident. He just kind of walks in the room and he knows the work that he's put in. And you can feel it, you can hear it. You can hear how he's talking. Again, just offseason preparation, his physicality and his confidence in trying new things. Our pitching coaches are asking him to push himself, and he's like, ‘All right, yeah, let's go.’ It's kind of a different Karson that we've seen over the past year evolving.”

Before season’s end, the Marlins rewarded Milbrandt with a promotion to Double-A Pensacola, where he allowed two runs over 10 2/3 frames across two starts. He then carried that over to the Arizona Fall League, where he was named a Fall Star with a 15.5 K/9 rate.

For the second straight offseason, Milbrandt added 20 pounds to his 6-foot-2 frame to be more physical on the mound and hold up during a long season. The opportunities continued for him this spring as a non-roster invitee at big league camp. In two Grapefruit League appearances, Milbrandt tossed two scoreless innings with one hit allowed, three strikeouts and no walks.

“I really like Karson,” manager Clayton McCullough said when the club reassigned him to Minor League camp. “He's coming off of a very good year going to the AFL. We were strategically judicious with his appearances and time in between his outings here in camp, with the long game of the season in mind with him. But he impressed and showed very good poise in the outings that he got out there, and it's a good pitch mix with some uniqueness and some deception funk to what he does.”

Command will be key for Milbrandt moving forward in his development. Though his walk percentage marginally dropped from 13 to 12.3 in 2025, the organization wants him to be in the zone more even if his arsenal allows him some wiggle room. Balkovec was confident this aspect of his game was coming.

Thursday served as a perfect example. Milbrandt limited the Astros’ prospects to just a run-scoring wild pitch despite walking three batters. His velocity maxed out at 97.1 mph, and he tallied strikeouts on three different pitches in his arsenal: slider (three), four-seamer (two) and curveball (one).

Milbrandt will return to Double-A Pensacola to begin 2026, hoping to pick up where he left off.

“Just continue to break out, trusting my stuff and going out there and attacking hitters,” Milbrandt said.