He's gotten fat and the move to United along with the WC to his head. It's as simple as that. He's not a good professional anymore. I think he used to be. But that's that. He still has time on his side, but he's neither improved his technical ability nor his reading of the game beyond the big man thug approach. Send him back to a relegation battler to set his head straight and arse whipped into shape.
He used to have a desire to be better to improve, to be the best he could be (despite limited ability).
Clearly, this all went to his head, he thought he made it, started to believe his own hype (no-one else hyped him), and started concentrating on things other than football (Jay Z). Too much money, too much exposure, appalling attitude, lazy and delusional about his own abilities.
Without effort and determination, all he has to fall back on his his appalling touch and inability to score against any half decent defence.
Thank god he is no longer our problem.