For those of you who don't know, UZR stands for Ultimate Zone Rating. It's possibly the most advanced defensive statistic available to the public. In fact, from 2003 until just recently, UZR wasn't available to the public because it's inventor, Mitchel Litchman, was hired by the Cardinals and the organization liked the statistic so much, they didn't want any other team to have access to it. But beginning last year, UZR and UZR/150 (UZR rating adjusted to 150 games) has been available on fangraphs.
So I thought I'd post the various range factors four or player (catchers don't get a range factor) so we can discuss the team's defensive ability. But keep in mind, the UZR isn't a perfect stat. It can get a little distorted when measuring outfielders especially because of strange ballpark sizes or outfielder positioning. UZR assumes that every player has the same "zone" they should be defending regardless of the batter, ballpark or players around them.
Anyways, here are their ratings according to UZR/150.
Kevin Youkilis: 10.7 at 1B, -0.7 at 3B
Dustin Pedroia: 6.4
Nick Green: 3.7
Mike Lowell: -16.4
Jason Bay: -9.3
Jacoby Ellsbury: -8.9
J.D. Drew: 11.9
A few surprises...
Mike Lowell's range looks horrible. Other players who have had hip surgery have shown similar drop in their range (Utley, A-Rod). Mark Kotsay's defense at first is really quite good (+16 last year, +17 so far this year). So temporarily moving him to 1st and Youkilis to 3rd while Lowell's hip heals should improve the defense quite a bit.
And the other big surprise is Ellbury's -8.9. This could just be a fluke result of the large CF in Fenway Park and those strange angles, which UZR doesn't account for. His ZR is one of the best in baseball among CF. But this suggests that he may not be an elite defensive CF and he has room for improvement.