Minnesota Twins pitchers ranked by win expectation above replacement level, lineup adjusted (WXRL).
NAME WXRL
Joe Nathan 6.58
Juan Rincon 3.20
Dennys Reyes 2.15
Pat Neshek 1.46
Matt Guerrier 0.77
Jesse Crain 0.59
Francisco Liriano 0.43
Carlos Silva 0.36
Matt Garza 0.31
Willie Eyre 0.21
Glen Perkins 0.17
Kyle Lohse -0.05
This stat (care of Keith Woolner at Baseball Prospectus) basically tracks how the probability of winning changes while each pitcher is in the game. If we put a replacement level pitcher on the mound in the ninth inning, then the Twins might not win if they are only ahead by one run. But if the Twins are ahead by eight or nine runs, then even if they put a bad pitcher on the mound, he'll probably get the job done.
So if Joe Nathan comes into the ninth inning when the Twins are up by only one run and he gets the save, he gets more credit than if Matt Guerrier comes into the game in the ninth inning with the Twins up by eight runs, since a lot more pitchers can get Guerrier's job done.
Anyway, for as good as Rincon, Reyes, and Neshek were this year, Nathan was worth almost as much as those guys combined. Together, that trio of set-up guys was worth about 6.8 wins, while Nathan was worth about 6.5 wins by himself. It still bothers me that he seems to lead the league in warning track fly outs, but it probably shouldn't. He's on the shortlist for the best closer in baseball.
Jesse Crain finishes low on this list, but most of that is April and May talking. Crain was transitioning from a low-strikeout pop-up pitcher back to a fastball/slider guy who gets a lot of strikeouts and groundballs. In general, it's a lot easier to succeed when you're striking out five more batters per nine innings than when you're scraping by with barely more strikeouts than walks, so I'm pretty optimistic about Crain's value going into next year.