First off, it doesn't matter why he overslept. For a kid who's had a checkered career at A&M, he needed to prove to his future employers that those transgressions were behind him. He did not. In fact, he pretty much proved what scouts and coaches have been saying about him since he landed at College Station. Secondly, he is not the best RB in the draft. He is questionable in pass protection and above average catching the football. He may be a serviceable RB in the NFL, but he is not a can't-miss stud.
He sure did not sleep through the drills. He had probably the best overall combine performance on the field out of all the RBs. He was a top 10 performer in all 7 drills!