Last with Arizona Diamondbacks · 1B · No longer on a 40-man roster
Peter O'Brien has an estimated 1 year and 1 day of major league service time — 1.001 in the notation clubs use, from 173 days credited on a major league roster.
| Season | Club | Days | Running total | How this season is known |
|---|---|---|---|---|
| 2015 | Arizona Diamondbacks | 27 | 0.027 | From transactions |
| 2016 | Arizona Diamondbacks | 54 | 0.081 | From transactions |
| 2017 | Kansas City Royals, Cincinnati Reds, Texas Rangers, Los Angeles Dodgers | 2 | 0.083 | From transactions |
| 2018 | Miami Marlins | 28 | 0.111 | From transactions |
| 2019 | Miami Marlins | 62 | 1.001 | 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.