Players · K · Pitcher · 2025
Jackson Kowar
- Age
- 29
- B/T
- R/R
- Height
- 6' 5"
- Weight
- 200 lb
- Number
- #57
- Born
- October 4, 1996 in Weddington, NC, United States
- MLB debut
- June 7, 2021
- Drafted
- 2018, round 1C
- College
- Florida
- High school
- Charlotte Christian
- dbWAR
- -1.1 4 season(s)
- IP
- 17.0
- ERA
- 4.24
- FIP
- 5.84
- K/9
- 7.9
- FIP−
- 140 100 = avg
Jackson Kowar was a relief pitcher for the Seattle Mariners. In 2025 he struck out 15 batters over 17.0 innings across 15 appearances, going 2-0. His ERA of 4.24 was 1.8% higher than the league average of 4.16. Stripping out defence, his 5.84 FIP suggests that his ERA had some help behind him. He missed bats on 25.2% of swings (12.1% of every pitch he threw), walked 9.9% of the batters he faced and struck out 21.1%. His -0.3 dbWAR is built from that FIP rather than runs allowed, so it credits him for what he controls and not for the defence behind him.
League context
Percentile among qualified pitchers, 2025.
WAR by season
Pitching
Standard and advanced, by season.
Platoon splits
How left- and right-handed hitters fare against him.
| Split | PA | AB | H | HR | BB | SO | AVG | OBP | SLG | wOBA | K% |
|---|---|---|---|---|---|---|---|---|---|---|---|
| vs LHB | 43 | 39 | 8 | 2 | 3 | 9 | .205 | .279 | .410 | .302 | 20.9% |
| vs RHB | 28 | 24 | 6 | 2 | 4 | 6 | .250 | .357 | .500 | .373 | 21.4% |
Pitch sequencing
What Jackson Kowar throws in each count, and what he follows each pitch with. Select any cell for the breakdown.
Select a count to see exactly what Jackson Kowar throws in it.
Pitch arsenal
What he throws, how hard, how often it misses, and what hitters do with it.
| Four-Seam Fastball | 162 | 97.3 | 2,167 | 45.1% | 12.8% | 42 | .238 | .765 | |
| Slider | 100 | 86.2 | 2,507 | 43.0% | 52.3% | 19 | .158 | .620 | |
| Changeup | 15 | 87.0 | 2,420 | 13.3% | 0.0% | 2 | — | — |
Head to head
Put Jackson Kowar beside up to three others.
wOBA uses linear weights measured from this season's own play-by-play rather than published constants, and wRC+ is park-adjusted against that same league. dbWAR is our own open implementation — not fWAR or bWAR — and the full derivation, including its simplifications, is on the methodology page.