| Home | Teams and Players | Homerun Kings | Top Salaries | Most Runs Batted In | Hall of Fame |
| Name | Jack O'Brien |
| Given Name | John Joseph |
| Birth Date | 1873-2-5 |
| Birth City | Watervliet, NY |
| Height | 6'1" |
| Weight | 165 lbs. |
| Batting Hand | Left |
| Pitching Hand | Right |
| Alive | No |
| Age | 60 |
| Year | Team | Hits | At Bats | Home Runs | Runs Batted | Batting Average | Wins | Losses | # of Pitching Games | Strikeouts | # of Shutouts |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1899 | Washington Senators | 132 | 468 | 6 | 51 | 0.282051 | |||||
| 1901 | Cleveland Blues | 8 | 45 | 0 | 5 | 0.177778 | |||||
| 1901 | Cleveland Blues | 106 | 375 | 0 | 39 | 0.282667 | |||||
| 1901 | Washington Senators | 8 | 45 | 0 | 5 | 0.177778 | |||||
| 1901 | Washington Senators | 106 | 375 | 0 | 39 | 0.282667 | |||||
| 1903 | Boston Americans | 71 | 338 | 3 | 38 | 0.210059 |
| Year | Position | Errors | Double Plays | Assists |
|---|---|---|---|---|
| 1899 | 3rd Base | 6 | 1 | 10 |
| 1899 | Outfielder | 23 | 5 | 21 |
| 1901 | 3rd Base | 0 | 0 | 2 |
| 1901 | Outfielder | 10 | 4 | 9 |
| 1901 | Outfielder | 2 | 0 | 0 |
| 1903 | 2nd Base | 4 | 0 | 7 |
| 1903 | 3rd Base | 3 | 3 | 15 |
| 1903 | Outfielder | 6 | 2 | 9 |
| 1903 | Shortstop | 0 | 0 | 0 |