Thiago choose the best for himself when the club didn't even try to hold on him and may be even showed the door.And he was actually class act and asked Bayern to have a good settlement with Barca than his buyout (though we were gonna get that anyway so they avoid taxes).There should be no hard feeling for both side and if one days it happens that we can get him and his ideal for us I won't go against it.but that isn't the situation right now with stacked midfield .
I support the club in the case of Thiago. You have a player who is getting minutes (he was by far the youngster with the most minutes in the team in his last season), but wants more and he tries to pressure the club to get more playing time. In 2012-13 he had 27 appearences in La Liga alone. So, he ACTUALLY DID PLAY in that season in La Liga. It's not like he played 6-7 games. He featured, more or less, in about 70% of the games. What the hell did he expect? To be an outright starter ahead of payers who were much better than him?
He thought he's going to Bayern to be their star midfielder, but he ended up playing 50 games in his 3 seasons there in Bundesliga. Around 17 games a season, less than half as a starter. He stagnated, isn't even a regular with the NT (which, IIRC, was one of the main reasons he left to Bayern - to get in Spain's team for the World Cup), and if Bayern sells him it's only because they think he is not good enough. And if he's not good enough for them, he sure as hell ain't good enough for Barca.
And about him comming back, it's not even a question of grudge against him. He's just not good enough to play in our team more than he did when he left, and he doesn't fit our needs in midfield at the moment.