I think he's either physically exhausted, playing through an injury, or just mentally checked out for some reason. He's talented enough that the points are still there but to my eye he just doesn't look as 'good' as he did in the first half of the season. I think I've disagreed with all but 1 of the diving calls I've seen against him, but he doesn't do himself any favors by chirping the refs as often as he does, or by being slow to get back up and into the play when he is taken down.
Again I don't really know why but I think he's kind of coasting right now, very little urgency in his game and prone to making some silly little mental errors right now that I didn't really see earlier.
Could just be that the league doesn't pose much of a challenge for him any more