William Kempner
Career Stats, Bio & Records (2026)
William Kempner is a pitcher who has played in Major League Baseball since 2026 for the Miami Marlins. Across 9 career appearances, he has gone 1-0 with a 2.92 ERA and 14 strikeouts.
- W (Wins):
- Games credited to a pitcher whose team took a lead it never surrendered while he was the pitcher of record.
- ERA (Earned Run Average):
- Earned runs allowed per nine innings pitched: (ER × 9) ÷ IP. The primary measure of pitching effectiveness.
- SO (Strikeouts):
- For a batter, times retired on a third strike; for a pitcher, batters retired on a third strike.
- WHIP (Walks and Hits per Inning Pitched):
- Baserunners allowed per inning: (BB + H) ÷ IP. Under 1.00 is elite.
Data updated
- Bats / Throws
- R / R
- Height / Weight
- 6'0" / 222 lb
- MLB Debut
- 2026-05-05
- Jersey
- #71
- Draft
- 2022
Full name: William Kempner Kempner
Season-by-Season Pitching
Click a stat to plot it across every season.
| Year | Team | Lg | W | L | G | GS | CG | SHO | SV | IP | H | ER | BB | SO | ERA | Lg ERA | Pitcher PIV |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | MIA | NL | 1 | 0 | 9 | 0 | 0 | 0 | 0 | 12.1 | 8 | 4 | 4 | 14 | 2.92 | 4.17 (+30%) | - |
| Career · 1 season | 1 | 0 | 9 | 0 | 0 | 0 | 0 | 12.1 | 8 | 4 | 4 | 14 | 2.92 | — | 0 | ||
Lg columns show the league average for that season, with the player's figure as a percentage above or below it. Career totals the seasons listed above.
William Kempner: the record in brief
The debut date in the bio is May 5, 2026; William Kempner is an active player, and this profile updates as the season goes on. Every season row on the page belongs to the Miami Marlins, in 2026. Height and weight on file: 6'0" and 222 pounds. Kempner was born on June 18, 2001, in San Jose, CA, USA.
Kempner's career pitching line is 1 win, 0 losses and a 2.92 ERA over 9 appearances. Kempner has 14 strikeouts. That 2.92 ERA compares with a 4.17 league average across the same seasons, 30.0% better. All of that pitching came in 2026, with 9 games and 14 strikeouts.
The draft line shows 2022.
Frequently Asked Questions about William Kempner
- Was William Kempner a pitcher?
- Yes. William Kempner pitched in the major leagues, recording 1 wins and 14 strikeouts.
- What was William Kempner's career ERA?
- William Kempner finished with a 2.92 career ERA, going 1-0 with 14 strikeouts.
- How many strikeouts did William Kempner have?
- William Kempner recorded 14 career strikeouts.
- Is William Kempner in the Hall of Fame?
- No. William Kempner has not been inducted into the National Baseball Hall of Fame.
- What teams did William Kempner play for?
- William Kempner played for the Miami Marlins.