Season A - 74 Innings, 47 Saves, 9 Runs, 5 Earned Runs, 2 Home Runs Allowed, 76 Strikeouts
Season B - 73 Innings, 48 Saves, 9 Runs, 5 Earned Runs, 2 Home Runs Allowed, 73 Strikeouts
Both pitchers posted the same ERA: 0.61.
Season B is Dennis Eckersley's 1990, probably his best season (as a reliever). However, that was not Eckersley's most heralded season. He finished fifth in the Cy Young balloting, sixth in MVP balloting; he'd fared almost exactly as well on both ballots the season before. It wasn't until 1992, when he led the majors with 51 saves and went 7-1, that Eckersley won the Cy Young and MVP Awards.
Why, exactly, did Eckersley win both big awards in '92 when he'd come close to winning neither in '90? Honestly, I don't know. As I've suggested before, I think the history of the awards is loaded with mysteries like this, and solutions will only come through a close examination of the contemporary accounts. Essentially, though, momentum is created in the media, and eventually the voters are somehow swept off their feet. In 1992, there were a number of starting pitchers with at least 20 wins and a number of starting pitchers without excellent other statistics ... but they were different starting pitchers. And there weren't many hitters with the sort of seasons that typically impress(ed) MVP voters.
I guess. Again, it's hard to say for sure without going back and digging into the newspaper archives.
But I digress (again). I suppose this is the point where I should mention that Season A up there is what Fernando Rodney has done this season. I should also mention that Rodney's and Eckersley's seasons weren't exactly the same. Most amazingly, Eckersley issued four walks all season, compared to 15 for Rodney. On the other hand, Rodney has given up only two doubles all season, compared to nine for Eckersley.
Essentially, they're having the same season except -- and this does matter to award voters -- Eckersley pitched for a postseason team and Rodney did not. Which is going to hurt Rodney in the awards voting, and especially in the MVP voting where he probably won't finish in the top 10.
Which is probably just about right. As great as Eckersley was in 1990 and Rodney has been this season, it's very difficult to construct a mathematical equation that will make them look like incredibly valuable players. They simply don't throw enough innings.
FanGraphs has Rodney with the highest Wins Above Replacement (2.4) among American League relief pitchers ... but lower than 20 starting pitchers. He fares a lot better at Baseball-Reference.com, with 3.7 WAR ... but still lower than 10 starting pitchers. The "problem" with relief pitchers is that even if you give them a massive bump for their psychological impact on their teams' fortunes -- say 2 extra Wins Above Replacement for the best, most reliable relievers -- they're still not going to come out ahead of the best starting pitchers. You know, because of the innings.
According to B-R.com, there's been just one reliever in major-league history who led his league in WAR: Rich Gossage in 1976, when he posted a 1.84 ERA in 142 innings, and went 9-8 with 26 saves. With 8.1 WAR, he's apparently the only reliever in history with more than 8 WAR in a season; there are only two others -- John Hiller in 1973, Mark Eichhorn in 1986 -- higher than 7.
Fernando Rodney's just finishing an absolutely incredible season; incredible because it came out of nowhere, and incredible because he's pitched incredibly well. But it's not been an incredibly valuable season, in the context of pitchers in general. There are really good reasons why relief pitchers don't fare as well as starters in the Cy Young balloting, and why they don't make as much money as starters.