Last with Washington Nationals · P · No longer on a 40-man roster
Mason Thompson has an estimated 4 years and 23 days of major league service time — 4.023 in the notation clubs use, from 711 days credited on a major league roster.
| Season | Club | Days | Running total | How this season is known |
|---|---|---|---|---|
| 2021 | Washington Nationals, San Diego Padres | 79 | 0.079 | From transactions |
| 2022 | Washington Nationals | 136 | 1.043 | From transactions |
| 2023 | Washington Nationals | 168 | 2.039 | From transactions |
| 2024 | Washington Nationals | 172 | 3.039 | From transactions |
| 2025 | Washington Nationals | 156 | 4.023 | 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.