| Home | Teams and Players | Homerun Kings | Top Salaries | Top RBIs | Hall of Fame |
| First Name | Last Name | Given Name | Birth Year | Birth Month | Birth Day | Birth City | Birth Country | Height | Weight | Age | Bats | Throws |
| Tom | O'Brien | Thomas J. | 1873 | 2 | 20 | Verona | USA | 71 | 170 | 27 |
| Year | Team | AB | HR | RBI | BA |
|---|---|---|---|---|---|
| 1897 | Baltimore Orioles | 147 | 0 | 32 | 0.2517 |
| 1898 | Baltimore Orioles | 60 | 0 | 14 | 0.2167 |
| 1898 | Pittsburgh Pirates | 413 | 1 | 45 | 0.2591 |
| 1899 | New York Giants | 573 | 6 | 77 | 0.2967 |
| 1900 | Pittsburgh Pirates | 376 | 3 | 61 | 0.2899 |
| Year | Team | W | L | G | SHO |
|---|---|---|---|---|---|
| 1897 | Baltimore Orioles | 0 | 0 | 0 | 0 |
| 1898 | Baltimore Orioles | 0 | 0 | 0 | 0 |
| 1898 | Pittsburgh Pirates | 0 | 0 | 0 | 0 |
| 1899 | New York Giants | 0 | 0 | 0 | 0 |
| 1900 | Pittsburgh Pirates | 0 | 0 | 0 | 0 |
| Year | Team | POS | E | DP | A |
|---|---|---|---|---|---|
| 1897 | Baltimore Orioles | 1B | 7 | 7 | 9 |
| 1897 | Baltimore Orioles | OF | 2 | 2 | 6 |
| 1898 | Baltimore Orioles | OF | 5 | 4 | 3 |
| 1898 | Pittsburgh Pirates | 1B | 6 | 12 | 4 |
| 1898 | Pittsburgh Pirates | 2B | 5 | 1 | 23 |
| 1898 | Pittsburgh Pirates | 3B | 4 | 1 | 10 |
| 1898 | Pittsburgh Pirates | OF | 13 | 4 | 15 |
| 1898 | Pittsburgh Pirates | SS | 7 | 1 | 11 |
| 1899 | New York Giants | 1B | 0 | 0 | 0 |
| 1899 | New York Giants | 2B | 0 | 2 | 3 |
| 1899 | New York Giants | 3B | 9 | 2 | 37 |
| 1899 | New York Giants | OF | 19 | 7 | 21 |
| 1899 | New York Giants | SS | 2 | 1 | 5 |
| 1900 | Pittsburgh Pirates | 1B | 28 | 37 | 26 |
| 1900 | Pittsburgh Pirates | 2B | 0 | 1 | 4 |
| 1900 | Pittsburgh Pirates | OF | 3 | 0 | 1 |
| 1900 | Pittsburgh Pirates | SS | 2 | 1 | 5 |