Thiago has not been the main culprit for Bayern in their disappointing eliminations. He has had some bad games and some very good ones, the attackers though have been completely misfiring for years in the CL. Thiago creates chances at a good enough level in many games, they just hardly ever finish them. Ribery, Lewandowski, Muller, etc. All have been poor.
Thiago isn't good enough to lead a CL winning team as its best player. But here at Barca he would have Messi, Coutinho, and Griezmann doing serious damage in the final third as well as Busquets behind him. That's a good enough support system for him to not need to do it all in the CL. Just keep the tempo rolling and play progressive passes, that's a majority of what Kroos does for RM in the Champions League these days.