So I ended up thinking a lot about and looking up a lot about and typing a lot about Ben Revere as an OF in the fanpost thread re: UZR. I figure I'd throw it up here and see what people think. It may seem like a no-brainer to stick him in left given his less-than-stellar arm, but poking around and looking at just how many defensive runs there are to be had in the various positions, I'm not so sure.
Here's what I wrote:
There is of course one throw that is longer from RF than from LF: the throw to 3rd. Having borderline guys take third on your right fielder is not good, so nearly every team with a noodle armed outfielder puts him in LF.
But where are most balls in the air that hang up for any length of time hit? Right field. This is a neat look at why.
OK, now if the Twins call Revere up, we can pretty safely assume the guy will bring extremely good range to any outfield position. If the "other" corner is still Delmon or Cuddyer and the "range" one of them brings to the table, there may well be more to be gained through putting Revere's range in RF (versus LF) than lost due to his below average arm. Taking away a bloop single altogether (of which most are hit to right field, since most hitters are right-handed [see the "neat look" link above) is just SO much more valuable than preventing a guy from going from first to third.
The same goes re: putting Revere in CF: taking away an extra base hit in the alley or over the head or a sinking linedrive would-be single is worth many extra bases taken by baserunners.
It comes down to how much of each circumstance happens, and how many more extra outs Revere would convert with his range in right (or center) field than in left field. Based on the fact that fielding metrics show a much wider spread of likely true talent for range than arm (Here is every RF with more than 300 innings, click "Arm" and "RngR" over on the right side to sort, maybe throw out the top couple on either end to simulate regression and eyeball the distribution), there's little doubt which it's more important to have in the absolute sense. (Answer: Range.)
And clicking over to left fielders the spreads aren't as wide as in right, which tells me there are indeed a lot less opportunities to help or do damage there, both with range and arm.
As was pointed out, Target Field has a big left field, and this might skew things a bit in favor of a rangey left fielder. However, it also seemed (standard ANECDOTE warning!) there were a ton of fliners hit to the right field alley last year for extra bases that Kubel or Cuddyer were only a couple steps from getting to.
In any case, the Twins will very probably put Revere in left if he comes up in 2012 and it'll all be moot, so we should be thankful Target Field is built such that his range will have more utility than it might in the average LF.
And this will be good. Delmon was -11 runs UZR/150 last year. The 32 year old version of Juan Pierre was 13.4 UZR/150 in LF last year (and I've never heard Revere's arm is as bad as that, although it's worth noting that Pierre's arm only actually cost him 2 runs). Assume Revere plays 2010 Pierre-like defense, which seems safe, and that's 24 runs, 2.4 wins/150 games. Damn girl.
OTOH, if he plays right and posts Jay Bruce's 2010 range of 19 runs saved per 150 games (he's faster than Bruce, though; indeed I believe he's faster than every single right fielder on the list, so he could be better) and his arm costs him 7 runs over such a span (this would be the same as the absolute worst rate for a right fielder in MLB), that's +12 runs UZR/150 vs. Cuddyer's -18.4 UZR/150 and Kubel's -16.8 UZR/150. 30 runs/3games! Even more improvement than replacing Delmon! It's possible that a healthy Cuddyer (albeit a year older) might be more like -12/150 or so, so it'd be a similar swap to the LF move.
But you know, looking at the CF talent spread and assuming Revere's speed is what it looks like it is, I think I like Span in right and Revere in centerfield, arm and all (with Cuddyer/Kubel in left). Click on ARM on the right side of this list of center fielders with 300 innings and you can see arm just ain't the big deal it's cracked up to be in centerfield (even allowing for some selection bias) but range can get you a ton of runs. There's a limit to how much help Revere's presumably extreme range gives you in RF compared to CF, where the XBH-denying potential is so much greater. You move the underperforming RFer to LF and you minimize his damage (by minimizing his chances, as discussed above), you get what should be Bruce-like range in RF and improve your CF defense, too.
Of course, these numbers are probably just bunk, etc...
This was actually pretty interesting to look at. I think I'll copy it in a fanpost.
EDIT: some additions from the other thread worth (I hope) adding:
Right Fielders save the most runs coming in to snag would-be bloop singles in front of them or tracking balls hit mid-distance down the line. Those are the balls that hang up, hit weakly on late or poking swings by right handed bats. Range makes a huge difference in terms of how many are outs and how many are singles (or doubles down the line). Truly DRIVEN balls tend to go out of the park/off the wall/be truly uncatchable (and hit to the pull field, which is LF, more often than not). The deep-playing RF alley in Target Field means a better Right Fielder might be able to save a bit there vs. say, the dome, too.
I was, as I tried to make clear, quite struck by how little CF arm seems to matter, for all the fuss people make regarding Revere’s arm not playing.
I mentioned selection bias above regarding this. That is, the idea that maybe arms APPEAR not to matter because all MLB center fielders have good arms, so nobody's terribly far from the really existing average. I said that I thought selection bias wasn't that important.
Here's a bit more explanation: the spread of arm factors in CF is narrow. If you look at 2010 CFs with 300+ innings and throw out the top outlier on each end (simulating regression to the mean and much better representing the group as a whole, in any case), the range is only +3.9 to -3.5 runs saved or given over the course of an entire season, which tells me center fielders don’t make enough throws where the outcome is in much doubt for it to count for nearly as much as people suppse. (RF, same formula, -4.8 to +6.2.)
Now, when he was a fulltime CF, Juan Pierre’s yearly arm factors averaged out to all of 5 runs below average. Remember, the selection bias idea would depend on all those CFs having strong arms AND that arm having real value, but the value being hidden by the relatively equivalent strength of everybody's arm. But Juan Pierre has a PATHETIC arm (I watched a lot of White Sox Baseball last year. Oh god is it bad), yet he was only thereby costing his team 5 runs (while posting range-run numbers from slightly to FAR above average). If CF arm mattered as much as some people think and there's a selection bias towards "cannons", it's not possible that Pierre's arm numbers would have been so inoffensive.
Bernie Williams in his twilight years was brought up as an example of what a bad arm in CF can cost a team. His last season arm-runs in center field, extrapolated as if he'd played as much as the busiest CFer in baseball last year (1350 innings) would have been worth about 8 runs below average. Let's say Revere's arm is THAT bad. (Which it really probably isn't.) If his range in 1350 innings is +18 – which he has the speed for it to be – IT DOESN’T FREAKING MATTER. He'd still be a great center fielder.
And again, I don’t think Revere’s arm is last-year Bernie Wililams or Juan Pierre bad.