I'm in a standard points league with 12 teams...(1 pt for each TB, -1 for K's, 1 for BB, 1 for SB, -1 for CS, .5 for R)

My starting shortstop is Carlos Guillen, who tends to get hurt every year for a little while, and my backup is Stephen Drew, who has done nothing this year...I'm thinking about dropping Drew, but I need a backup...

The top waiver wire guys are:

Khalil Greene
Alex Gonzalez
Yuniesky Betancourt
Troy Tulowitzki

Greene is my first thought since he's been hitting pretty well lately and has a low BABIP (.251). Tulowitzki has also been decent lately, but his BABIP is like .330, and I'm thinking he's due to come back down. Not sure what I think about Gonzalez, although he's in the GABP, and Betancourt doesn't really excite me much...

Who would you choose?