| 2012 NL Leaders | |||||||||||||
| Name | Age | Team | G | IP | TBF | BB% | K% | BABIP | LOB% | GB% | HR/Air | ERA | FIP |
| Brad Ziegler | 33 | Arizona | 77 | 68.67 | 263 | 8.0% | 16.0% | .267 | 75% | 77% | 4% | 2.49 | 3.24 |
| Bryan Morris | 25 | Pittsburgh | 5 | 5.00 | 20 | 10.0% | 30.0% | .200 | 60% | 73% | 0% | 1.80 | 2.53 |
| Daniel Otero | San Francisco | 12 | 12.33 | 57 | 3.5% | 14.0% | .409 | 50% | 71% | 0% | 5.84 | 2.80 | |
| Phillippe Aumont | 24 | Philadelphia | 18 | 14.67 | 65 | 13.8% | 21.5% | .263 | 70% | 70% | 0% | 3.68 | 3.26 |
| Jenrry Mejia | NY Mets | 5 | 16.00 | 74 | 12.2% | 10.8% | .333 | 73% | 70% | 12% | 5.63 | 5.44 | |
| Jamey Wright | 38 | LA Dodgers | 66 | 67.67 | 306 | 9.8% | 17.6% | .340 | 69% | 69% | 3% | 3.72 | 3.42 |
| Randy Choate | 37 | LA Dodgers | 36 | 13.33 | 64 | 14.1% | 17.2% | .333 | 75% | 68% | 8% | 4.05 | 4.93 |
| Ronald Belizario | LA Dodgers | 68 | 71.00 | 286 | 10.1% | 24.1% | .250 | 77% | 65% | 5% | 2.54 | 3.13 | |
| Eric O'Flaherty | 27 | Atlanta | 64 | 57.33 | 230 | 8.3% | 20.0% | .286 | 85% | 63% | 5% | 1.73 | 3.30 |
| Justin Hampson | 32 | NY Mets | 13 | 10.00 | 37 | 13.5% | 10.8% | .222 | 64% | 63% | 0% | 1.80 | 3.83 |
| Jonathan Venters | Atlanta | 66 | 58.67 | 262 | 10.7% | 26.3% | .369 | 83% | 62% | 10% | 3.22 | 3.79 | |
| Todd Coffey | 32 | LA Dodgers | 23 | 19.33 | 83 | 10.8% | 21.7% | .314 | 64% | 62% | 5% | 4.66 | 3.64 |
| Steven Edlefsen | San Francisco | 14 | 15.33 | 69 | 8.7% | 13.0% | .358 | 73% | 61% | 5% | 4.70 | 3.98 | |
| Trevor Cahill | 24 | Arizona | 32 | 200.00 | 839 | 8.8% | 18.6% | .297 | 71% | 61% | 7% | 3.78 | 3.88 |
| Jeremy Affeldt | 33 | San Francisco | 67 | 63.33 | 267 | 8.6% | 21.3% | .315 | 74% | 61% | 1% | 2.70 | 2.76 |
| Bobby Parnell | 28 | NY Mets | 74 | 68.67 | 288 | 6.9% | 21.2% | .309 | 77% | 61% | 5% | 2.49 | 3.03 |
| Sean Burnett | 30 | Washington | 70 | 56.67 | 239 | 5.0% | 23.8% | .344 | 85% | 60% | 6% | 2.38 | 2.83 |
| Tim Stauffer | 30 | San Diego | 1 | 5.00 | 24 | 12.5% | 20.8% | .400 | 70% | 60% | 16% | 5.40 | 5.53 |
| Tony Cingrani | Cincinnati | 3 | 5.00 | 22 | 9.1% | 40.9% | .300 | 109% | 60% | 23% | 1.80 | 3.33 | |
| Marc Rzepczynski | St. Louis | 70 | 46.67 | 196 | 8.7% | 16.8% | .285 | 77% | 59% | 12% | 4.24 | 4.76 | |
| Jared Hughes | 27 | Pittsburgh | 66 | 75.67 | 316 | 7.0% | 15.8% | .254 | 75% | 59% | 7% | 2.85 | 4.08 |
| Matt Albers | 30 | Arizona | 23 | 21.00 | 84 | 8.3% | 22.6% | .245 | 86% | 59% | 13% | 2.57 | 4.32 |
| Brandon League | 29 | LA Dodgers | 28 | 27.33 | 108 | 13.0% | 25.0% | .274 | 78% | 59% | 0% | 2.31 | 2.80 |
| Cory Gearrin | Atlanta | 22 | 20.00 | 80 | 6.3% | 25.0% | .308 | 88% | 58% | 4% | 1.80 | 2.83 | |
| A.J. Burnett | 36 | Pittsburgh | 31 | 202.33 | 851 | 7.3% | 21.2% | .301 | 74% | 58% | 7% | 3.51 | 3.56 |
| Lucas Harrell | 27 | Houston | 32 | 193.67 | 827 | 9.4% | 16.9% | .301 | 71% | 58% | 5% | 3.76 | 3.78 |
| Jeff Suppan | 38 | San Diego | 6 | 30.67 | 137 | 9.5% | 5.1% | .280 | 68% | 58% | 8% | 5.28 | 5.64 |
| Sean Marshall | 30 | Cincinnati | 73 | 61.00 | 256 | 6.3% | 28.9% | .329 | 80% | 58% | 4% | 2.51 | 2.28 |
| Javier Lopez | 35 | San Francisco | 70 | 36.00 | 153 | 9.2% | 18.3% | .343 | 77% | 58% | 2% | 2.75 | 3.10 |
| Kameron Loe | 31 | Milwaukee | 70 | 68.33 | 303 | 6.6% | 18.2% | .330 | 68% | 57% | 9% | 4.61 | 4.24 |
