Cesc was the best player in the Premier League but then struggled when he came to Barca. Alexis was the best player in Serie A, he's also struggled. The fact that Thiago even fits in at all shows how much quality he has, let alone the flashes of genius he shows multiple times in every game he plays. He makes a few mistakes, but those are perfectly in keeping with his immaturity. How many times does Cesc give the ball away? Or what about Messi(remember Stamford Bridge last season)?