The only other guys that would have been returning that aren't - besides McClain - are Scott Dean (backup C from Knoxville) and Ryan Butner (P from Florida). Only losing 3 players at this point is about par for the course. College baseball yearly roster attrition is sometimes mindboggling.
BTW - I'm basing this information solely off our fall baseball roster on utsports.com. There could be reasons why these 3 were left off the roster (grades, discipline); it's happened in the past.