Well, it's never a good thing when a player leaves the program, regardless of his location on the depth chart. Most folks probably don't know much or anything about red-shirt freshman Chris Rock. He obviously sat out 2011 during his red-shirt year, and he didn't really make a name for himself at the spring game last month, so his departure likely to have very minimal impact on the D-line going forward.
Chris gained quite a bit of interest during his recruitment. The 6-5, 250 pound defensive end out of Columbus was pursued by Michigan State, Nebraska, Notre Dame, Oregon, Ohio State, Pitt, UCLA, Stanford, WVU, Wisconsin...just to name a few.
At the time, this was a very nice get for Rodriguez in the summer of 2010. He just never panned out once he got on campus. Not that all uncommon of a tale, I suppose. Best of luck to Chris in whatever he decides to do.