Of the 135 relievers who threw at least 50 innings:
| Wins | Pitchers | % |
| 4+ W | 1 | 0.74 |
| 3+ W | 3 | 2.22 |
| 2+ W | 14 | 10.4 |
| 1+ W | 47 | 34.8 |
| 0+ W | 115 | 85.2 |
| Negative | 20 | 14.8 |
Yes, you are reading that correctly. There were more negative value types than 2+ win types. Unless you are paying for a relief ace (and there doesn't appear to be too many of those), you may as well non-roster invite a bunch of promising arms and have a cheap and interchangeable bullpen.
Mariano Rivera was the lone 4+ W reliever. He had perhaps the best season of his closer career, which is saying a lot. He was worth 4.2 wins, equal to James Shields.