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| Name | Pos | Team | Age | DOB | POB | Nationality | Bats | Throws | Height | Weight | Salary |
| O'Day, Greg | C | Free Agent | 32 | 06/30/1986 | Greenville | USA | Right | Right | 6' 0" | 178 lbs | - |
| Ocampo, Diego | C | Detroit X-Wings | 25 | 12/13/1993 | Santo Domingo | DOM | Right | Right | 6' 1" | 220 lbs | - |
| Oglethorpe, Tom | CF | Charlotte Jackals | 32 | 10/16/1986 | Beckley | USA | Left | Left | 6' 2" | 169 lbs | $6,880,000 |
| Ohayashi, Masahiko | C | Charlotte Jackals | 30 | 09/21/1988 | Komatsushima | JPN | Right | Right | 6' 1" | 207 lbs | - |
| Ohayashi, Yoshiaki | RF | Indiana Hounds | 23 | 02/16/1995 | Bizen | JPN | Left | Left | 6' 4" | 205 lbs | - |
| Omori, Takaaki | SP | Allentown Hillbillies | 23 | 05/27/1995 | Hirosaki | JPN | Switch | Left | 6' 1" | 215 lbs | - |
| Orosco, Armando | C | Indiana Hounds | 32 | 11/01/1986 | Santo Domingo | DOM | Right | Right | 6' 3" | 233 lbs | - |
| Orosco, Arturo | C | Allentown Hillbillies | 31 | 01/02/1987 | Amarillo | USA | Right | Right | 5' 10" | 195 lbs | - |
| Ortíz, Carlos | SS | Topeka Tornados | 22 | 02/24/1996 | Cataño | PUR | Right | Right | 6' 0" | 170 lbs | - |
| Ortíz, Gustavo | 3B | Indiana Hounds | 24 | 05/08/1994 | San Pablo de las Salinas | MEX | Right | Right | 6' 0" | 220 lbs | - |
| Osborn, Alex | CL | Waba Ducks | 29 | 12/31/1989 | Trumbull | USA | Right | Right | 6' 7" | 243 lbs | - |
| Ou, Luo-shan | 3B | Portland Privateers | 30 | 04/13/1988 | Toronto | CAN | Right | Right | 6' 3" | 206 lbs | - |
| Owens, Dante | RF | Portland Privateers | 18 | 07/08/2000 | Vernon | CAN | Left | Left | 6' 6" | 165 lbs | - |
