The problem Julio had in high school was similar to the one he had with VT. He was double and triple teamed in high school, and it eventually resulted in his playing injured his whole senior year.
As a result, I don't think he has ever learned how to deal with a double-team while he has his full physical capacities. I saw last Saturday about three situations where he was within a hairbreadth's of making the catch, but he allowed one of the defenders to hit the ball and jostle it from his grasp.
I think that Julio still hasn't come to terms with his own strength and therefore with his potential to outmuscle defenders. A perfect example was the overtime catch against LSU last year, when Patrick Peterson was able to grab Julio's shirttail and keep him from scoring. I think that if Julio had reached back with his free arm and swiped Peterson's arm, he probably could have freed himself and scored.
The same thing last Saturday night -- here were those DB's who looked sort of like gnats around Julio's head and shoulders, and he still was not as physical with them as he is capable of being. Once he realizes that even in Division 1A football he is stronger than the DB's, he probably will reach the kind of savvy that the pro receivers have, meaning he becomes more in tune with his own physicality in relation to the DB's covering him.
"Hit or get hit" is the old football adage. If you take the game TO the defense, you have already gained an advantage. Julio is still letting the DB's take the game to HIM, IMHO.