Let’s completely ignore sample size issues for a moment, shall we? In this outfield this season (prior to last night’s game, even), Marcus Thames has an UZR/150 of -17.4. Such a rating is inline with Thames’ previous fielding trends while with the Tigers. Basically, though this was made especially clear during last night’s game, he is the worst outfield defender on the Yankees’ roster. However, with Nick Swisher out, unless fans want to see the offensively anemic Greg Golson receive a ton of extra at-bats, Joe Girardi is forced to play him in the outfield (he has wisely shifted Thames over to right field, though, where there is less ground to cover, overall).
At the beginning of the year, Girardi actually played Thames in left, and seemingly had to learn just how bad Thames was with a glove through trial and error. I think it is pretty clear now that he is downright miserable, fielding-wise (even I did not think he would be this bad). When Swisher returns, the Yankees will have to employ Thames (and Miranda) at DH, because, regardless of his hitting, Thames is too much of a defensive liability to play in the outfield.