Don't expect a Mariano Rivera decline

Mariano Rivera, at age 41, should look a lot like he did at age 40. Getty Images

In April 2005, when Mariano Rivera blew two saves against the Boston Red Sox after blowing two games in the previous year's ALCS, skeptics began to predict his downfall. In 2006, he lost a couple of games in April and the wolves again licked their chops, waiting for the decline of the great Rivera. In 2007 it was certain: He had allowed four runs to the Red Sox while recording just one out. Mariano Rivera, postseason hero, closer extraordinaire, had finally reached the end of the line.

Only he didn't.

Each time he bounced back from those early season woes to produce yet another stellar season. Even in 2007, when he allowed nine runs in his first 6.2 innings, he recovered to post a 2.23 ERA the rest of the way. It seems as though he goes through one of those rough patches every year, but he compensates for it with sheer domination otherwise. In seven of the past eight seasons he has produced an ERA of 2.00 or lower; that includes 2010, his age-40 season.

With the World Series behind us, Rivera, for just the second time in his career, is a free agent. That is, essentially, a status in name only. Rivera will certainly return to the only team he has ever known. After winning the World Series in 2009, Rivera's fifth championship, he said that he'd play for five more years if he could. While the Yankees won't sign him to pitch through 2014, they will certainly take care of their closer. It's difficult to fathom where they'd be without him.

While he has a long history of dominance, not even Rivera can continue pitching forever. He turns 41 later this month, an age at which most pitchers are at home with their wives and kids. Only 108 pitchers in history have made an appearance at age 41, and few of them have lived up to Rivera's lofty standards. How, then, can we project how he's going to perform in his own age 41 season if we have so few comparables?