March 22, 2013
Recently, Mariano Rivera revealed that 2013 would be his final season. It wasn’t unexpected news, in that Rivera is 43 years old and coming off a serious injury that caused him to consider retirement in 2012. But the report, however predictable, hit many fans hard. Not only is Rivera respected and beloved both inside and outside of New York (a relative rarity for a big, bad Yankee), but he’s shown so little erosion in his skills that it’s possible to picture him throwing his cutter until he turns 50. Most players go through a decline phase, which gives us time to get used to the idea that it’s about to be over. Rivera really hasn’t, except in the sense that he’s less durable than he once was.
Rivera’s announcement inspired many written responses, one of which was an email to me from a reader named David Greene. “Rivera’s true ranking among pitchers all-time,” the subject line said.
How good is Rivera, really? And is it possible to compare him to baseball’s best starters?
Last season, Aroldis Chapman was probably the best reliever in baseball. (“Craig Kimbrel” is also an acceptable answer). PWARP put him at 2.6 wins, which made him the 27th-most-valuable pitcher in baseball, by that metric. He was so good as a reliever, in fact, that he nearly placed out of the bullpen, briefly becoming a candidate to start this season.
In 1996, Mariano Rivera was worth almost twice what Chapman was last year. That season, AL pitchers allowed 1.21 home runs per nine innings, the highest rate ever. Rivera allowed one home run in 107 2/3 innings, the lowest rate of any AL pitcher in the DH era. He posted the highest strikeout rate and the lowest FIP of his career, and he pitched almost 30 more innings than he has in any season since. Then he added 14 scoreless frames in the postseason. If you count those October innings, Rivera’s 1996 was the most valuable season ever by a pitcher who didn’t make a single start.*