I really don't understand the people who are saying that Thiago is a traitor or what so ever. I am a big Barca fan, but really he made the best choice of his life. At the moment he decided to leave Barcelona he was in a situation where he was used as a back-up player. Not even a rotation player. That season Barcelona was already champion and even then Vilanova didn't let him play. And then one of the best teams in the world want you really, what would you do?
Let's accept it, it was really bad management off Vilanova and Zubi.
For me he is one off the best midfielders of the world at the moment. And it is scary that he can only get better. The role that he played yesterday against Arsenal is the role that suites him the best. As a deep-lying playmaker who can roam around the pitch, and dictate play. On many occassions Guardiola has used Thiago as an advanced playmaker, but he then can dissapear from a game.
At Bayern they play the game that is perfect for him, possession based and dominate matches. Unfortunately, at Barcelona they now play a sort off counter attack/direct game within this type off midfielders don't suit. Just look at the bad stats of Iniesta last season. Like I said, he made the best choice off his life to join Bayern and he will compete for Balon D'or on a really short term.