Boston Red Sox · P · Arbitration eligible
Zack Kelly has an estimated 3 years and 72 days of major league service time — 3.072 in the notation clubs use, from 588 days credited on a major league roster.
| Season | Club | Days | Running total | How this season is known |
|---|---|---|---|---|
| 2022 | Boston Red Sox | 38 | 0.038 | From transactions |
| 2023 | Boston Red Sox | 172 | 1.038 | From transactions |
| 2024 | Boston Red Sox | 135 | 2.001 | From transactions |
| 2025 | Boston Red Sox | 125 | 2.126 | From transactions |
| 2026 | Boston Red Sox | 118 | 3.072 | From transactions |
172 days credit a full year, so a season adds at most 1.000 no matter how long a player is on a roster. 3.000 years reaches salary arbitration and 6.000 reaches free agency —
what every threshold unlocks.
This figure is an estimate reconstructed from public roster
transaction records. It is not an official MLB or MLBPA figure — those are
not published. See the
methodology.
Last updated 2026-10-12.
Independent project, not affiliated with or endorsed by Major League
Baseball or the MLBPA.