One of the topics that interests me most in sabermetrics is what I call "spectrum equilibrium." We all know that certain positions are nominally harder to play and that there's a premium for defense at those positions. There's also an ability to contribute runs/wins despite having a negative offensive or defensive contribution if the opposite contribution is great enough.

The easy example is Derek Jeter. It's a never ending debate about Jeter's value, including a recent and amazingly ignorant NY Times article. This year, Jeter had a +3 Fielding Rating, changing the discussion slightly. In 2003, Jeter put up a -21 rating. His offensive value of 53.9 VORP translates out to 32 by simple math, but there's better than simple available.

WARP3 includes defense and gives Jeter a 4.7 WARP3, meaning that the negative fielding rating doesn't have quite the negative effect we'd expect. Now, I don't know the numbers behind any of these ratings, so we'll just trust in the BP braintrust. For those of you that like Win Shares, WARP3 shows similar results - Jeter's 26 Win Shares are a near match to his 8.9 WARP3. (Win Shares for some unknown reason equal 1/3 of a win.)

So, no matter how bad Jeter's defense was (or how he improved this season), Jeter's bat made it smart for the Yankees to play him there. We'll never know how the team might have been changed by Alex Rodriguez playing short, so why bother worrying. My interest is more in figuring how we can find the best configuration to maximize the win potential of a team.

Could Manny Ramirez play shortstop? If only for comedic value, the answer would be yes, but just how bad would it be? I'd be curious if he'd be bad enough to turn his 70 VORP into a negative. Actually, the more interesting question is if he would have a -55 rating, since Orlando Cabrera had a 15.2 VORP and a -1 FR. (What? -1 for the "defensive wizard"?)

The Red Sox make this decision with an offensive player with a bad fielding reputation and a player with a stellar defensive reputation and a decent stick each day. Kevin Millar has gotten most of the starts down the stretch for the Red Sox despite Doug Mientkiewicz's rep as a glove man. Once again, the numbers don't match up. Minky comes back with a -5 FR in Boston (0 in Minnesota) while Millar had a +1!" We know Boston knows numbers, so Millar's 5.3 WARP3 is a clear choice above Minky's 0.9.

There's a lot of work to be done on this subject, but it all might be rendered moot by the advances of technology. MLB's "true range" project might render all this moot by making an exciting advance -- one that will be sabermetric yet not mathematical.

** All defensive numbers are available on the amazing Davenport Translation cards at BP. Call me biased, but they're one of the best baseball tools I've seen. **