| Name | Pos | Team | Age | DOB | POB | Nationality | Bats | Throws | Height | Weight | Salary |
| O'Beirne, Dusty | MR | Georgia Bulldogs | 21 | 09/06/1995 | Long Beach | USA | Right | Right | 6' 0" | 250 lbs | - |
| O'Brennan, Victor | LF | Wake Forest Demon Deacans | 21 | 04/27/1995 | Lacey | USA | Right | Right | 6' 1" | 155 lbs | - |
| O'Brien, Dan | 3B | Free Agent | 22 | 09/14/1994 | Tuckahoe | USA | Left | Right | 6' 5" | 205 lbs | - |
| O'Brien, Howard | CL | Free Agent | 23 | 02/21/1993 | Alameda | USA | Left | Left | 5' 6" | 180 lbs | - |
| O'Cahill, Dexter | 1B | Oregon Ducks | 19 | 02/11/1997 | Ashland | USA | Right | Right | 6' 0" | 235 lbs | - |
| O'Callaghan, Dave | CF | Florida State Seminoles | 21 | 04/01/1995 | Beaverton | USA | Right | Right | 6' 0" | 185 lbs | - |
| O'Connor, Carson | 2B | Mississippi State Bulldogs | 21 | 03/06/1995 | Cherry Hill | USA | Right | Right | 6' 1" | 180 lbs | - |
| O'Doherty, Danny | 2B | Free Agent | 22 | 06/15/1994 | Ft. Worth | USA | Right | Right | 6' 1" | 155 lbs | - |
| O'Donnell, Tim | SP | Free Agent | 26 | 10/06/1990 | Saddle Brook | USA | Right | Right | 6' 4" | 203 lbs | - |
| O'Dowling, Howard | CF | Stanford Cardinals | 20 | 01/18/1996 | Westport | USA | Left | Left | 6' 3" | 210 lbs | - |
| O'Farrell, Steve | RF | Clemson Tigers | 20 | 04/07/1996 | Boston | USA | Switch | Right | 6' 1" | 185 lbs | - |
| O'Farrell, Tom | RF | Free Agent | 25 | 07/01/1991 | Dyer | USA | Right | Right | 6' 1" | 197 lbs | - |
| O'Halloran, Johnny | RF | Free Agent | 23 | 03/09/1993 | Rosemont | USA | Left | Left | 5' 8" | 175 lbs | - |
| O'Hanvey, Bob | 2B | Free Agent | 23 | 01/05/1993 | Chicago | USA | Right | Right | 6' 0" | 205 lbs | - |
| O'Haydon, Randall | CF | Kansas Jayhawks | 21 | 04/15/1995 | Erie | USA | Right | Right | 6' 3" | 185 lbs | - |
| O'Herlihy, Jack | SP | Free Agent | 23 | 04/10/1993 | Valley Station | USA | Right | Right | 6' 6" | 240 lbs | - |
| O'Keefe, Artie | CF | Free Agent | 22 | 01/23/1994 | Ooltewah | USA | Right | Right | 6' 3" | 200 lbs | - |
| O'Lehan, Will | 1B | Free Agent | 22 | 04/18/1994 | New York | USA | Right | Right | 6' 0" | 205 lbs | - |
| O'Monaghan, Will | SS | Stanford Cardinals | 20 | 05/31/1996 | Arvada | USA | Right | Right | 5' 10" | 200 lbs | - |
| O'Neal, Ernie | CF | USC Trojans | 20 | 11/26/1996 | Manhattan | USA | Left | Left | 6' 2" | 170 lbs | - |
| O'Neal, Joe | CF | Free Agent | 23 | 10/06/1993 | Flint | USA | Right | Right | 6' 2" | 220 lbs | - |
| O'Neal, Nick | MR | Free Agent | 22 | 02/10/1994 | Frankfort | USA | Right | Right | 6' 0" | 172 lbs | - |
| O'Neal, Rob | CF | Texas Longhorns | 21 | 09/17/1995 | New Iberia | USA | Right | Right | 6' 1" | 215 lbs | - |
| O'Neal, Trevor | SP | Free Agent | 22 | 10/21/1994 | Louisville | USA | Left | Right | 5' 11" | 220 lbs | - |
| O'Neil, Mark | LF | Miami Hurricanes | 20 | 09/03/1996 | Fairlawn | USA | Left | Left | 6' 0" | 155 lbs | - |
| O'Neil, Martin | C | Louisiana-Layfayette Ragin Cajuns | 19 | 11/11/1997 | Greenville | USA | Right | Right | 6' 0" | 200 lbs | - |
| O'Neil, Sam | 3B | Houston Cougars | 21 | 06/05/1995 | Fairborn | USA | Right | Right | 6' 0" | 185 lbs | - |
| O'Neill, Doug | 3B | Free Agent | 24 | 02/21/1992 | Nashville | USA | Left | Right | 5' 11" | 185 lbs | - |
| O'Neill, Eric | CF | Georgia Bulldogs | 18 | 04/28/1998 | Milledgeville | USA | Right | Right | 6' 1" | 160 lbs | - |
| O'Quinn, Bill | CF | Free Agent | 23 | 01/08/1993 | Kennesaw | USA | Right | Left | 6' 5" | 180 lbs | - |
| O'Quinn, Dave | RF | Free Agent | 23 | 03/19/1993 | Cheyenne | USA | Right | Left | 6' 0" | 205 lbs | - |
| O'Quinn, Eric | CF | Arkansas Razorbacks | 20 | 08/18/1996 | Gainesville | USA | Right | Right | 6' 0" | 175 lbs | - |
| O'Quinn, Kevin | 1B | Free Agent | 22 | 10/21/1994 | New York | USA | Left | Right | 6' 6" | 230 lbs | - |
| O'Quinsalen, Nick | MR | Clemson Tigers | 21 | 02/08/1995 | Brockton | USA | Left | Right | 6' 6" | 215 lbs | - |
| O'Rourke, Josh | 3B | Stanford Cardinals | 21 | 10/19/1995 | New Iberia | USA | Right | Right | 6' 0" | 180 lbs | - |
| O'Slattery, Frank | 2B | Oklahoma State Cowboys | 19 | 01/25/1997 | Thomasville | USA | Right | Right | 6' 0" | 185 lbs | - |
| O'Toole, Charles | 2B | Florida State Seminoles | 19 | 10/19/1997 | Morgan Hill | USA | Right | Right | 6' 3" | 205 lbs | - |
| O'Toole, Willie | 3B | UCLA Bruins | 21 | 10/28/1995 | Lake Shore | USA | Right | Right | 5' 10" | 195 lbs | - |
| Ochoa, Cisco | 1B | Ohio State Buckeyes | 21 | 04/30/1995 | Humacao | PUR | Right | Right | 6' 6" | 236 lbs | - |
| Ochoa, Juan | SP | Washington State Cougars | 18 | 02/02/1998 | Santiago | DOM | Right | Right | 5' 11" | 240 lbs | - |
| Ochoa, Miguel | 1B | Kansas Jayhawks | 21 | 02/24/1995 | Sulphur Springs | USA | Switch | Left | 6' 1" | 185 lbs | - |
| Oglethorpe, Corey | 1B | Oregon Ducks | 21 | 04/27/1995 | Fontana | USA | Left | Left | 6' 0" | 240 lbs | - |
| Ognenovic, Zeljko | 3B | Rice Owls | 20 | 10/10/1996 | Covington | USA | Switch | Right | 5' 9" | 180 lbs | - |
| Ojeda, Norberto | RF | Free Agent | 22 | 02/01/1994 | Seaside | USA | Right | Right | 6' 0" | 190 lbs | - |
| Olarte, Alberto | LF | Tennessee Volunteers | 21 | 09/29/1995 | Panama | PAN | Right | Right | 6' 0" | 220 lbs | - |
| Oliva, Gustavo | 2B | Washington State Cougars | 20 | 04/30/1996 | Lubbock | USA | Right | Right | 6' 2" | 205 lbs | - |
| Olivas, Fernando | MR | Georgia Bulldogs | 19 | 02/15/1997 | Westminster | USA | Right | Right | 6' 1" | 200 lbs | - |
| Oliver, B.J. | SP | Free Agent | 22 | 08/04/1994 | Manasota Key | USA | Left | Left | 5' 9" | 210 lbs | - |
| Oliver, Dan | SP | Free Agent | 22 | 10/31/1994 | Queens | USA | Right | Right | 5' 10" | 230 lbs | - |
| Oliver, Denny | 2B | Virginia Cavaliers | 21 | 12/30/1995 | Lincoln | USA | Right | Right | 6' 2" | 175 lbs | - |
| Oliver, John | CF | Free Agent | 24 | 01/05/1992 | Spartanburg | USA | Right | Right | 6' 0" | 175 lbs | - |
| Olsen, Kevin | RF | Free Agent | 23 | 12/16/1993 | Green Valley | USA | Left | Right | 6' 2" | 165 lbs | - |
| Olson, Bob | 2B | Free Agent | 22 | 07/20/1994 | Alamosa | USA | Right | Right | 6' 1" | 165 lbs | - |
| Olson, Dexter | MR | Florida State Seminoles | 21 | 12/31/1995 | Lexington | USA | Right | Right | 6' 4" | 235 lbs | - |
| Olson, Mark | 3B | Arkansas Razorbacks | 21 | 12/31/1995 | Bronx | USA | Right | Right | 6' 0" | 185 lbs | - |
| Olvera, Jesús | MR | Rice Owls | 20 | 06/20/1996 | Greeley | USA | Right | Right | 6' 7" | 240 lbs | - |
| Olvera, Luis | SP | UCLA Bruins | 21 | 12/19/1995 | Payson | USA | Left | Right | 6' 2" | 220 lbs | - |
| Ordway, Bill | C | California Golden Bears | 21 | 10/02/1995 | Los Angeles | USA | Switch | Right | 5' 11" | 185 lbs | - |
| Orozco, Armando | MR | Free Agent | 22 | 10/28/1994 | Plano | USA | Switch | Right | 6' 6" | 200 lbs | - |
| Orozco, Felipe | RF | Fresno State Bulldogs | 21 | 03/12/1995 | Pachuca | MEX | Left | Left | 5' 11" | 180 lbs | - |
| Orr, Gary | MR | Rice Owls | 19 | 06/02/1997 | Killeen | USA | Right | Right | 6' 2" | 195 lbs | - |
| Orr, Steve | MR | Arizona Wildcats | 20 | 11/28/1996 | Meridian | USA | Right | Right | 6' 3" | 185 lbs | - |
| Orr, Warren | SP | South Mississippi Golden Eagles | 19 | 12/02/1997 | Ross Township | USA | Right | Left | 6' 1" | 225 lbs | - |
| Ortega, Alonso | SP | TCU Horned Frogs | 21 | 02/16/1995 | La Romana | DOM | Right | Right | 5' 11" | 205 lbs | - |
| Ortega, Manuel | SS | Baylor Bears | 20 | 05/26/1996 | Jarabacoa | DOM | Left | Right | 6' 1" | 210 lbs | - |
| Ortíz, Alejandro | 3B | Mississippi State Bulldogs | 21 | 11/07/1995 | St. Petersburg | USA | Right | Right | 6' 2" | 215 lbs | - |
| Ortíz, Carlos | 3B | Free Agent | 23 | 10/04/1993 | Caracas | VEN | Right | Right | 6' 1" | 225 lbs | - |
| Ortíz, Diego | SS | Kansas Jayhawks | 19 | 11/29/1997 | La Victoria | VEN | Switch | Right | 6' 3" | 205 lbs | - |
| Ortíz, Diego | CF | Clemson Tigers | 19 | 06/23/1997 | Santiago | DOM | Left | Left | 6' 1" | 175 lbs | - |
| Ortíz, Felipe | RF | Houston Cougars | 21 | 11/12/1995 | Kailua (Honolulu County) | USA | Left | Left | 6' 3" | 215 lbs | - |
| Ortíz, Jorge | 3B | Florida State Seminoles | 21 | 03/16/1995 | Yucaipa | USA | Left | Right | 5' 9" | 200 lbs | - |
| Ortíz, José | MR | Free Agent | 22 | 11/04/1994 | Beech Grove | USA | Left | Left | 6' 1" | 225 lbs | - |
| Ortíz, Juan | SS | Free Agent | 23 | 08/05/1993 | Thornton | USA | Switch | Right | 6' 0" | 190 lbs | - |
| Ortíz, Manny | CF | Rice Owls | 21 | 07/24/1995 | Newport News | USA | Left | Left | 5' 11" | 170 lbs | - |
| Ortíz, Rafael | RF | South Mississippi Golden Eagles | 19 | 12/27/1997 | Santo Domingo | DOM | Left | Left | 5' 10" | 185 lbs | - |
| Ortíz, Raúl | 1B | Ohio State Buckeyes | 19 | 05/19/1997 | Valencia | VEN | Switch | Left | 6' 3" | 215 lbs | - |
| Osorio, Jaime | C | Free Agent | 23 | 10/07/1993 | Arecibo | PUR | Right | Right | 6' 0" | 215 lbs | - |
| Osorio, Ricardo | 1B | Georgia Tech Yellow Jackets | 21 | 03/21/1995 | Martinsville | USA | Right | Right | 5' 11" | 200 lbs | - |
| Ospira, Rafael | SS | Oklahoma Sooners | 20 | 12/18/1996 | Phoenix | USA | Left | Right | 6' 3" | 185 lbs | - |
| Ostendorff, Sal | LF | Alabama Crimson Tide | 21 | 07/17/1995 | Bonneauville | USA | Left | Right | 5' 8" | 205 lbs | - |
| Otero, Jesús | 1B | Free Agent | 25 | 10/22/1991 | San Diego | USA | Right | Right | 6' 0" | 247 lbs | - |
| Ovsienko, Fabi | 3B | Florida Gators | 22 | 11/12/1994 | Hicksville | USA | Left | Right | 5' 11" | 190 lbs | - |
| Owen, Jason | C | Free Agent | 24 | 08/07/1992 | Chesapeake | USA | Right | Right | 6' 4" | 210 lbs | - |
| Owen, Kyle | RF | LSU Tigers | 20 | 10/01/1996 | San Antonio | USA | Left | Left | 5' 11" | 195 lbs | - |
| Owens, Dominic | LF | Arizona State Sun Devils | 21 | 05/31/1995 | Martinez | USA | Left | Right | 6' 0" | 195 lbs | - |
| Owens, Lane | 1B | Free Agent | 23 | 11/13/1993 | Mystic Island | USA | Switch | Right | 6' 2" | 205 lbs | - |
| Owens, Patrick | SP | Baylor Bears | 20 | 07/26/1996 | Lompoc | USA | Right | Left | 5' 10" | 225 lbs | - |
| Owens, Sherwood | 2B | Free Agent | 24 | 06/11/1992 | Brockton | USA | Left | Right | 6' 0" | 195 lbs | - |