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| "O" Pitching Register | |
| Batting Register | Pitching Glossary |
| Player | From-To | W | L | Pct | ERA | G | GS | CG | SHO | SV | IP | H | ER | HR | BB | SO |
| Joey Obrien | 2022-2025 | 14 | 32 | .304 | 6.15 | 324 | 0 | 0 | 0 | 31 | 391.0 | 440 | 267 | 80 | 241 | 281 |
| Albert Ocampo | 2013-2024 | 140 | 122 | .534 | 4.24 | 387 | 338 | 53 | 9 | 0 | 2379.3 | 2403 | 1122 | 400 | 466 | 1148 |
| Mauro Occhipinti | 2001-2011 | 79 | 102 | .436 | 5.76 | 237 | 231 | 11 | 3 | 0 | 1419.5 | 1811 | 908 | 141 | 489 | 920 |
| Bryon Ohare | 2012-2017 | 12 | 78 | .133 | 6.74 | 179 | 120 | 0 | 0 | 4 | 666.7 | 886 | 499 | 89 | 448 | 421 |
| Tino Ojeda | 2022-2025 | 18 | 6 | .750 | 4.15 | 180 | 0 | 0 | 0 | 26 | 251.7 | 305 | 116 | 32 | 69 | 127 |
| Colin Oldham | 2015-2025 | 138 | 72 | .657 | 2.79 | 345 | 339 | 2 | 2 | 1 | 1959.3 | 1456 | 607 | 133 | 707 | 1477 |
| Gabriel Oles | 2021-2025 | 29 | 36 | .446 | 5.81 | 101 | 100 | 2 | 1 | 1 | 535.7 | 577 | 346 | 62 | 294 | 408 |
| Cirilo Olivarez | 2020-2025 | 6 | 3 | .667 | 7.12 | 62 | 0 | 0 | 0 | 5 | 67.0 | 86 | 53 | 6 | 47 | 47 |
| Joel Oliveros | 2011-2019 | 28 | 44 | .389 | 5.23 | 106 | 101 | 4 | 1 | 0 | 584.7 | 673 | 340 | 107 | 115 | 372 |
| Oswaldo Olmos | 2015-2025 | 87 | 98 | .470 | 4.48 | 313 | 294 | 5 | 1 | 1 | 1636.6 | 1701 | 815 | 204 | 396 | 893 |
| Lester Olson | 2001-2016 | 227 | 170 | .572 | 3.29 | 535 | 524 | 30 | 10 | 1 | 3362.9 | 3040 | 1231 | 267 | 1064 | 1892 |
| Raymundo O'Neill | 2004-2012 | 21 | 22 | .488 | 4.10 | 285 | 0 | 0 | 0 | 27 | 425.4 | 414 | 194 | 43 | 133 | 211 |
| Javier Oquendo | 2018-2025 | 10 | 28 | .263 | 7.99 | 350 | 0 | 0 | 0 | 19 | 550.0 | 656 | 488 | 116 | 480 | 301 |
| Peter Ordway | 2002-2010 | 15 | 62 | .195 | 8.35 | 122 | 113 | 1 | 0 | 1 | 522.7 | 843 | 485 | 97 | 216 | 275 |
| Antonio Ornelas | 2014-2016 | 13 | 4 | .765 | 4.58 | 143 | 0 | 0 | 0 | 5 | 235.7 | 246 | 120 | 26 | 59 | 117 |
| Ismael Orosco | 2014-2024 | 46 | 41 | .529 | 3.80 | 560 | 0 | 0 | 0 | 190 | 750.3 | 770 | 317 | 85 | 160 | 380 |
| Matthew Orourke | 2004-2016 | 36 | 39 | .480 | 4.71 | 705 | 3 | 0 | 0 | 56 | 1006.3 | 916 | 527 | 201 | 319 | 533 |
| Glen Orris | 2020-2025 | 30 | 33 | .476 | 5.81 | 143 | 96 | 0 | 0 | 4 | 523.3 | 524 | 338 | 89 | 392 | 340 |
| Steven Orris | 2002-2009 | 35 | 46 | .432 | 4.82 | 441 | 0 | 0 | 0 | 106 | 556.7 | 570 | 298 | 63 | 268 | 555 |
| Floyd Orta | 2014-2025 | 69 | 44 | .611 | 4.11 | 748 | 5 | 0 | 0 | 58 | 1111.7 | 1176 | 508 | 61 | 456 | 529 |
| JC Ortega | 2011-2025 | 25 | 26 | .490 | 6.75 | 443 | 0 | 0 | 0 | 39 | 527.0 | 614 | 395 | 111 | 351 | 166 |
| Alejandro Ortiz | 2022-2025 | 12 | 14 | .462 | 5.16 | 242 | 0 | 0 | 0 | 15 | 350.3 | 377 | 201 | 76 | 73 | 201 |
| Francesco Ortiz | 2012-2025 | 64 | 62 | .508 | 4.44 | 833 | 0 | 0 | 0 | 176 | 1108.0 | 901 | 547 | 114 | 574 | 972 |
| Julio Ortiz | 2014-2017 | 4 | 25 | .138 | 7.25 | 41 | 32 | 0 | 0 | 0 | 175.0 | 258 | 141 | 40 | 58 | 114 |
| Oscar Ortiz | 2021-2025 | 19 | 18 | .514 | 5.47 | 57 | 55 | 5 | 1 | 1 | 353.7 | 375 | 215 | 53 | 151 | 256 |
| Jason Osborne | 2001-2006 | 45 | 62 | .421 | 5.60 | 159 | 143 | 3 | 1 | 0 | 816.7 | 988 | 508 | 129 | 363 | 755 |
| Paul Osborne | 2001-2012 | 74 | 55 | .574 | 3.76 | 808 | 1 | 0 | 0 | 72 | 1060.4 | 1016 | 443 | 100 | 374 | 675 |
| Eldridge Oshea | 2008-2024 | 207 | 168 | .552 | 3.62 | 538 | 445 | 164 | 39 | 6 | 3433.9 | 3432 | 1382 | 402 | 542 | 1681 |
| Ken O'Sullivan | 2018-2025 | 63 | 69 | .477 | 4.45 | 215 | 215 | 5 | 1 | 0 | 1194.7 | 1242 | 591 | 200 | 212 | 845 |
| Pedro Osuna | 2020-2023 | 4 | 11 | .267 | 6.99 | 139 | 0 | 0 | 0 | 5 | 189.3 | 239 | 147 | 35 | 129 | 75 |
| Player | From-To | W | L | Pct | ERA | G | GS | CG | SHO | SV | IP | H | ER | HR | BB | SO |
| Harry Otte | 2009-2014 | 30 | 57 | .345 | 4.72 | 104 | 100 | 21 | 2 | 0 | 695.7 | 776 | 365 | 117 | 311 | 233 |
| Doyle Oubre | 2015-2025 | 41 | 37 | .526 | 4.23 | 613 | 0 | 0 | 0 | 41 | 929.6 | 924 | 437 | 88 | 459 | 712 |
| Francisco Oubre | 2020-2025 | 30 | 16 | .652 | 3.91 | 70 | 57 | 11 | 2 | 1 | 421.3 | 374 | 183 | 45 | 181 | 246 |
| Jonathan Ouellette | 2015-2015 | 2 | 3 | .400 | 6.08 | 6 | 6 | 0 | 0 | 0 | 40.0 | 46 | 27 | 5 | 19 | 32 |
| David Owens | 2001-2002 | 0 | 6 | .000 | 6.65 | 31 | 9 | 0 | 0 | 2 | 62.3 | 82 | 46 | 4 | 28 | 48 |
| Les Ownby | 2001-2015 | 188 | 136 | .580 | 4.00 | 424 | 424 | 40 | 16 | 0 | 2853.7 | 2928 | 1268 | 371 | 619 | 1861 |
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