Basenerd Banner
Loading games...
William Kempner
William Kempner
Miami Marlins • Pitcher
Age 25 • 6' 0" • 222 lb
Bats: R • Throws: R
MLB Debut: 2026-05-05
Born: San Jose , CA • USA
Draft: 2022
2026 Stats
W
1
L
0
ERA
2.92
WHIP
0.97
IP
12.1
SO
14
SV
0
HLD
0
G
9
GS
0
Career Stats
W
1
L
0
ERA
2.92
WHIP
0.97
IP
12.1
SO
14
SV
0
HLD
0
G
9
GS
0
Year-by-Year Pitching
Year Team GGSIP WLSVSO ERAWHIPAwards
2026 MIA 9 — 12.1 1 — — 14 2.92 0.97
Spring Training
Pitching
YearTeamGGSIPWLSVSOERAWHIP
2025 MIA 4—2.2 ———4 6.751.50
2026 MIA 4—4.0 ——16 0.000.75
Game Logs
Season selector loads one year at a time.
Pitching
Date Opponent IP H R ER BB SO HR
2026-07-11 vs CLE 2.0 3 2 2 0 3 0
2026-07-09 vs SEA 0.1 2 2 2 2 0 1
2026-07-03 @ ATH 1.0 0 0 0 0 1 0
2026-06-15 @ PHI 2.1 0 0 0 0 2 0
2026-06-10 vs AZ 2.0 0 0 0 2 3 0
2026-06-05 vs TB 1.1 1 0 0 0 1 0
2026-05-31 @ NYM 1.1 2 0 0 0 3 0
2026-05-30 @ NYM 1.0 0 0 0 0 0 0
2026-05-05 vs BAL 1.0 0 0 0 0 1 0
Transactions
Entire history • newest first.
2026-07-12
Miami Marlins placed RHP William Kempner on the 15-day injured list. Right elbow sprain.
2026-07-03
Miami Marlins recalled RHP William Kempner from Jacksonville Jumbo Shrimp.
2026-06-16
Miami Marlins optioned RHP William Kempner to Jacksonville Jumbo Shrimp.
2026-05-30
Miami Marlins recalled RHP William Kempner from Jacksonville Jumbo Shrimp.
2026-05-06
Miami Marlins optioned RHP William Kempner to Jacksonville Jumbo Shrimp.
2026-05-05
Miami Marlins recalled RHP William Kempner from Jacksonville Jumbo Shrimp.
2026-03-08
Miami Marlins optioned RHP William Kempner to Jacksonville Jumbo Shrimp.
2025-11-18
Miami Marlins selected the contract of RHP William Kempner from Jacksonville Jumbo Shrimp.
2025-02-28
RHP William Kempner assigned to Miami Marlins.
2025-01-15
San Francisco Giants traded RHP William Kempner to Miami Marlins for Future Considerations. International Bonus Pool Money.
2022-07-28
San Francisco Giants signed RHP William Kempner.
Scouting Report
Statcast-style percentiles • Basenerd theme
Season 2026
Ready
Basic Line
Season / Game
Loading…
Pitch Arsenal
Usage • Velo • Break • Spin • xwOBA
Pitch N Use% Velo HB IVB Spin xwOBA Whiff% Zone% Chase% BNStuff+ BNCtrl+
Loading…
Notes
Primary pitch summary
—
Movement Profile (Induced Break)
Pitcher's View: HB vs Rise / Drop (in)
Circles: 12/18/24 in • Dots = pitch types (size ~ pitch count)
Pitch Location Heatmaps
KDE-style blur • fixed zone • catcher POV
vs. LHH
vs. RHH
Zone: left -0.7083 / right 0.7083 • bot 1.595 / top 3.394 • Domain: X [-2,2], Z [0,5]
Statcast Game Log
Per-game pitch metrics from Statcast
Date Pitches Velo BNStuff+ BNCtrl+ Whiff% Zone% Chase% K% BB% xwOBA
Loading…
More