ERA+
Jackson Kowar · Season-by-season history
ERA+ over time
- Kansas City Royals · MLB
- Seattle Mariners · MLB
Hover over a point for its value. Only numeric values with a recorded season are charted; missing seasons are not treated as zero.
| Season | Team | League | ERA+ |
|---|---|---|---|
| 2025 |  Seattle Mariners |
MLB | 91 |
| 2023 |  Kansas City Royals |
MLB | 70 |
| 2022 | Kansas City Royals |
MLB | 43 |
| 2021 | Kansas City Royals |
MLB | 41 |