I just hope no one loses their heads over these Bayern defeats and suggests we should swap half the team and make numerous transfers. The problem is management, not players. Sure, a few need to leave, and we only need 2-3 new players to have the absolute perfect squad. But other than that, the players we have at our disposal are more than enough to make once again the best team in the world... with the right management.
+1.
Aside from the defense, the players aren't the main problem. I think the only things we really need are a GK, a CB, and a striker (if Villa leaves). Maybe a 2nd CB for depth and/or a winger (Neymar, Reus, etc), but those 2 aren't desperately needed.
Like you and I both said, the players aren't the main problem, even though a few are still needed. We have players like:
Messi - arguably the greatest player ever
Iniesta - best midfielder in the world, 3rd best player
Xavi - one of the best midfielders in the world, despite his age
Busquets - arguably the best CDM in the world
Villa - Spain's all-time top scorer. Still world-class despite his age and that injury last season.
Fabregas (on our bench, no less) - world-class midfielder, despite his poor second half of the season
Alba - arguably the best LB in the world
Not to mention players like Pique and Alves, who, despite their inconsistency, can still put in world-class performances. We've got good players on our bench too, such as Song, Thiago, etc.
The only starters who really need to be replaced (IMO) are Valdes (since he's leaving), Puyol, Villa (if he goes) and maybe Pedro (though Sanchez has been pretty good lately, maybe we could go with him in the starting XI next season?).
IMO, our main 2 problems in big games this season were tactics and motivation. Which is why I think we need a new coach.