It hasn't done much to his first-round status, rather just kept him out of the top half of the round, at least in the mocks. This ESPN.com report from May indicates situations where scouts were unable to check the progress of his breaking ball and especially the changeup, and the left-hander has lost development time on top of it all.
This is what BA had to say about the Rangers' mock selection:
Bet on a high-upside play here. It could be one of the higher-priced prepsters such as McCullers, Russell or Seager. Texas has been mentioned as much as anyone on Ohio high school lefthander Matt Smoral, a likely mid-first-rounder before he broke a bone in his foot and missed most of the year. Maybe the Rangers could make a run at Giolito. They also like Hensley and Davis, who probably can't get this far. Berrios and Brinson are possibilities, too.