He has a pedigree, as he was KG's number 2 prospect in the Braves system in 2007, achieving what he then called "very good prospect" status.  Jumping forward to 2008, he fell to a "3 star" (thanks for the consistent nomenclature, dude).  The main issue being the difference between his stuff and results.  His K rate has never been anything near what Goldstein thought his stuff should allow for.  In any case, he's got a good changeup and a live, sinking fastball that he can get up to 94 but generally sits in the low 90's.  The Rangers, apparently, have been working on adding a slider to his arsenal, but it doesn't appear to be helping his K rate so far.  It should help him reverse his splits, as lefties hit him very well according to KG.  Checking out minor league splits, it looks like evidence of the sinker is pretty stark: .119 ISO allowed.  Righties have somewhat more success than lefties, but as KG said, the stuff is clearly there.  It's control that's hurt him the most in AAA so far.  If he's throwing good strikes, it begins to look like a bad matchup for us.