Dimitrov. I would expect that he will only get better. The scale of his recent chokes was concerning, however, we are talking about matches against the very best.
Tomic on the other hand, I wouldn't be surprised if his ranking drops. Nothing would surprise me really.
Losing 3 sets against Murray x2 and Djokovic after being 5-2 up is seriously concerning. Yes,he is young but still should have a bit more confidence
He defnitely has the game to challenge the top guys though.