Not enough days in 1999 season to compile WAA record.
| Date | Rank | WAA | TeamID |
|---|---|---|---|
| 19990416 | XXXXX | 0.01 | NYA |
| 19990430 | XXXXX | 0.52 | NYA |
| 19990514 | XXXXX | 0.76 | NYA |
| 19990528 | +100+ | 1.38 | NYA |
| 19990611 | +074+ | 1.91 | NYA |
| 19990625 | +077+ | 2.15 | NYA |
| 19990709 | +088+ | 2.31 | NYA |
| 19990726 | +184+ | 1.44 | NYA |
| 19990809 | +136+ | 2.12 | NYA |
| 19990823 | +106+ | 2.68 | NYA |
| 19990906 | +092+ | 3.25 | NYA |
| 19990920 | +076+ | 3.88 | NYA |
| 19991004 | +065+ | 4.64 | NYA |
Mariano Rivera Post Season Games
| Rank | WAA | IP | ERA | Gs | Gr | Tm |
|---|---|---|---|---|---|---|
| +001+ | 9.3 | 141 | 0.77 | 0 | 96 | NYA |
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