All DT's (except Osa) averaged 30% of the snaps... and what I meant by "deep end of the pool" was the NFL as a whole. He had the measurables, but he was unprepared to play at this level, but we knew this when he was drafted. Is it not the coach's responsibility to make sure a player is ready?
What if he's not (or you're not sure), why play him? (Other than to gain "on the job training"). If he does struggle, do accept it with a grain of salt and allow him to continue?
IMO, after one year, it's a coach problem, if after 2-3 years, then, yeah, it's a player problem.