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Gotta agree with Matt.  Each year I am less enthused with UZR.  First off, it's based on a foundation that I believe has flaws.  (I think the official UZR scorers in "some cities" skew results -- and if the basic ZR is tainted, then everything behind it just goes completely bonkers).  Of course, I think in "most" cities the assessments are reasonable -- but on occasion the team UZR and DER results end up so vastly different from each other that it defies all reason.
But, the positional adjustments are the arena where I think the system completely and utterly falls apart and I don't like the underlying oversimplification that essentially says - if you strap the tools of ignorance on Jason Giambi, he gets 2-WAR BEFORE HE MAKES A PLAY.  (I know Tango's system actually gives catchers the highest positional adjustment, which is 2, IIRC).  I think SS is 1.5.  Moreover, the positional adjustments have ZERO to do with actually playing defense.  They were generated based on salary differentials.  I suspect when AROD moved from SS to 3B, every player at BOTH positions had their positional adjustments ... adjusted.
This is, (IMO), a case where the original ideal was to try and get a read on relative PAYROLL value between players - so one might clear up some of the fog in judging 1B for SS trades and such.  In that regard, this approach may well be excellent.  But, because that was the goal, the actual attention to defensive performance has been shoved to the back of the bus, rendering (IMO), UZR essentially useless for actually discussing defensive prowess, and in many cases, ultimately detrimental.
Honestly, if you go to Fangraphs and pull up ALL fielders, (auto-sorted by raw UZR), many things leap out as questionable to downright bizarre.
Gutierrez posted a 29.1 UZR -- (total runs saved), beating the next best glove in all of baseball, (Longoria - 18.5), by more than 10 runs.  That's a HUGE margin. 
Another oddity is that 4 of the top 7 run savers by UZR were third basemen.  4-3B, 2-LF, and 1-CF made up the top 7 run-saving gloves.  Does it really make sense that there would be a trio of LFs who saved more total runs than the 2nd CF?!?  Crawford, DeJesus and Juan Rivera, (plus RF Nelson Cruz), all ranked as saving more runs than the #2 CF (Upton). 
Jack Wilson, with a 14.0 UZR, saved more runs than any other SS, (while only playing 105 games?!?).  The #2 SS?  Cesar Izturies, (who played 112).  Then Everett (116).  You have to get all the way down to Rafael Furcal with a UZR of 8.0, before you get a SS who played the whole season, (149 games).  The fact that Furcal was tied with Ibanez with a URZ of 8.0 just strikes me as inexplicable.  UZR says that Ibanez saved as many runs, (in his 129 games), as the BEST full-time SS in baseball. 
According to UZR, Wilson was the best SS in baseball - (14.0 UZR and a 20.4 UZR/150), while YuBet was the worst, (by far), -20.5 raw -23.9 UZR/150.  Does ANYONE believe that EVERY other qualifying SS in baseball fits between those two in defensive runs saved?  Yes, the Ms DER improved a tad after Yuni left.  Is the difference between Wilson and Yubet REALLY more than 40 runs?  Per UZR/150, the diff was 43.9.  Can it REALLY be that big? 
I don't honestly know.  But, I see soooo many things about UZR when I scan the lists that just don't "feel" right -- not just a little off -- but drastically off what the eyes (and other stats) suggest -- that I cannot accept UZR as a valid stat for judging defensive prowess.  At this point ... I'd feel about as comfortable judging a fielder based off of UZR (alone), as I would judging a pitcher based off "runners picked off" alone.