William Kempner

William Kempner: live stats, Statcast data and splits for the Miami Marlins right-handed pitcher.

William Kempner's 2026 season

William Kempner pitched in 9 games out of the bullpen for the Miami Marlins in 2026, the season he made his MLB debut on May 5. The right-hander worked 12⅓ innings with a 2.92 ERA and a 0.97 WHIP, striking out 14 (28.0 percent of batters) and walking 4 (8.0 percent). He was worth 0.1 fWAR.

Before his call-up, he posted a 3.98 ERA over 31⅔ innings at Triple-A Jacksonville Jumbo.

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William Kempner's 2026 season

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PODCAST: Why trading Logan Gilbert should be on the table, blockbuster prospect trades, Ryan Sloan’s trade value

PODCAST: 3B Prospects, how the D improves, every arbitration decision

The J.P. Crawford Paradox

PODCAST: 3 Mariners players that should be on the trade block