I think there is a little of both sides. Some think he is and will be a bust, mostly b/c he was a first-rounder. Others think he is starting to come around and will be just fine.
Both are opinions. Neither are right or wrong at this point. In the long run, what Stubbs is doing right now doesn't matter. It's what he will be doing in the long run and beyond.
But for now, I don't think anyone can dispute that he hasn't had the best start for his career.