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.