The Marlins optioned Kempner to Triple-A Jacksonville on Sunday.
Kempner was added to Miami's 40-man roster in November but was never a likely bet to crack the Opening Day roster. The 24-year-old had a quality showing in his first taste of Triple-A last year with a 2.65 ERA, 1.35 WHIP and 25:15 K:BB over 17 innings, and he could make his MLB debut at some point in 2026 if he continues to pitch well for Jacksonville.
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Marlins' William Kempner: Joins 40-man roster
Rotowire
The Marlins selected Kempner's contract from Triple-A Jacksonville on Tuesday.
Kempner was acquired from the Giants last winter in exchange for international bonus pool space, and the Marlins won't leave him exposed to potentially being selected during the upcoming Rule 5 Draft. Across three minor-league levels in 2025, the 24-year-old pitched to a 2.26 ERA, 1.15 WHIP and 95:40 K:BB over 67.2 innings.
