I don't know what has happened to him. He needs to leave and go to a smaller, counterattacking team.
I still have some faith in him, but he does need to be a bit more assertive. He's Messi's bitch right now; all he does is get the ball, run a bit and pass it to Messi.
I thought there was some signs in the Atletico game that he might be getting back. Hopefully it happens. The lack of goals isn't even the biggest problem because he's never been a prolific goalscorer, but at the moment he's not imposing his game at all. I'm blaming your system's high standards to match for outsiders, but no doubt its his own fault too.