If Rosberg hadn't dominated the tail-end of 2015 I would be inclined to say Hamilton would be leading this year as he did last, but for whatever reason Hamilton took his eye off the ball after winning the title last season and who's to say he would be ahead of Rosberg this year given a level playing field? They've been pretty level throughout the season in most sessions.
Yes Hamilton has had some terrible luck (and equally made his own mistakes at the start), but he was never going to catch let alone beat Rosberg on Sunday. Rosberg was just taking it easy through the traffic, as any leader without pressure would, and when he wanted to at the end he turned it up just to prove a point, even stopping Massa getting the fastest lap on his new super-softs.