McRoberts didn't had a good rookie season because he was injured; he didn't appear in most of the games that season due to that.
He didn't get the ball much in LA because, you know, Kobe.. We now know; one of Josh's greatest strengths is the ability to pass the ball. Kobe doesn't like that!
And finally I think all of the citizens of Orlando have kicked themselves in the back of the head at least a couple times after they've seen how McBob preformed playing for the Bobcats. I don't know exactly what it was: maybe he just didn't fit in in Florida, or perhaps the other big men (including Davis) were just better. But why should I care about all of that? He's playing great thus far!!