William KempnerMIA · RP

2026 review

William Kempner was a swing-and-miss reliever who barely stayed on the mound long enough to show it, posting a 2.92 ERA and 0.97 WHIP in 12.1 IP with a 28.0 K% and an 8.0 BB% over 50 BF across 9 games for MIA. He was optioned Mar 8, recalled May 5, optioned again the next day, recalled May 30, optioned Jun 16, and recalled Jul 3, shuttling up and down all season before a right elbow sprain put him on the 15-day IL Jul 12 and then the 60-day IL Aug 21, missing 77 regular-season days with no activation on record through Sep 27. Undrafted, he finished 466th of 1472 in the TDK LABS 5x5 value rank and 147th of 575 relievers. The TDK LABS card watched him arrive with one perfect inning before getting optioned to make room on May 8, then come back after a scoreless run to debut with scoreless frames by Jul 10 in a thin pen, before landing on the 60-day IL by Sep 19 with no clear role to return to.