This was one of the best teams that Barca has ever beaten. RM was just fantastic for most of this game.
Not every Barca player had his best game, but this team does not need that. What I am optimistic about for the rest of the season:
Lots and lots and lots of scoring chances are being created. Enough to win almost every game, and on the good shooting nights, win big. When you have M + N +S, you really only need one to be at his peak at any time. Sure, Neymar is in a bizarre period right now, but Neymar carried this team many games in the first half.
The defense is consitently resilient. When you hold RM to one, that is damn good D. Among the players Lucho keeping in the mix in the big games, there are no defensive weak links. The team is even getting good defensive work from unlikely sources like Messi and Neymar.
This squad just plays like champions. They don't look for excuses, they don't blame the ref, they thrive on two games a week. Someone rises to the occasion, even in the inevitable games when the team is less inspired.
To have a chance against Barca, you have to put out a stupendous effort. Like RM did in the first half. It is pretty close to impossible to do this for the full game, so Barca will always have the advantage when the opponents tire late in the game.