Marlins’ William Kempner To Undergo Elbow Surgery

Marlins manager Clayton McCullough announced Wednesday that righty William Kempner will undergo elbow surgery. Specifics weren’t provided, but Marlins.tv host Craig Mish suggested an absence of 12 to 14 months. If that’s indeed the case, it would likely point to a UCL-related procedure. In some instances, surgeons don’t know whether a full ligament reconstruction (Tommy John surgery) or less-severe internal brace is needed until they begin the operation and get a clearer look at the damage. The team will surely provide further specifics when they’re available.

It’s a tough blow for the promising young righty. Kempner made his big league debut earlier this season and has pitched 12 1/3 innings out of the Miami bullpen. The 25-year-old has held opponents to four runs (2.92 ERA) on eight hits and four walks. He’s punched out 14 of his 50 opponents while working off a four-seam/sinker/cutter/slider mix and working in a very occasional changeup (2.5%). Kempner sits 95.5 mph on the four-seamer and 94 mph on his two-seamer, while his slider clocks in around 81.5 mph.

Kempner has been impressive for the Marlins in the upper minors, too, and looked like a potential long-term option in McCullough’s bullpen. The former Gonzaga standout carries a 3.51 ERA and massive 36.2% strikeout rate in parts of two Triple-A seasons. Command has been an issue, as evidenced by last year’s 14% walk rate and a 15% mark in Triple-A this year, though Kempner only walked four of 50 opponents in the majors (8%).

Originally a third-round pick by the Giants in 2022, Kempner came to the Marlins in a Jan. 2025 trade that sent international bonus space back to San Francisco. The Giants had lined up a significant bonus for then-amateur infielder Josuar Gonzalez, who now ranks at the top of their system and has emerged as a consensus top-50 prospect in the entire sport. Adding the bonus space helped the Giants round out that year’s class, and in exchange they gave Miami an upside arm who’d missed the prior season due to injuries — namely a fractured foot.

Kempner’s injury means he’ll now miss yet another entire season’s worth of games, though this time the silver lining will be accruing a full year or more of major league service time and the associated pay that comes with it. Miami can move him to the 60-day injured list whenever they next need to open a 40-man roster spot, and he’ll be eligible to move back to the 60-day IL for the entire 2027 season as well.

There’s better news for Marlins starter Max Meyer, who’s been out for nearly a month due to a neck strain. McCullough noted that Meyer received a cortisone injection. The team is hopeful that will allow him to resume throwing soon. The Marlins still anticipate the 27-year-old returning at some point this season.

Meyer, the No. 3 overall draft pick back in 2020, has had a breakout season. The former University of Minnesota star has pitched 111 innings of 2.68 ERA ball, whiffing 26.2% of his opponents against an 8.9% walk rate along the way. He’s kept 41% of his opponents’ batted balls on the ground and averaged under one homer per nine innings pitched (0.89).

The trio of Meyer, Eury Pérez and Sandy Alcantara give the Marlins the nucleus for a nice rotation heading into 2027. Miami still controls him for three additional seasons, though he’s already reached arbitration as a Super Two player. He’s earning $980K this year and will have three more arbitration raises coming his way — likely a significant one this time around, given the strength of his breakout performance.