Liverpool messed up against Barca. Changed how they usually play - only played 2 instead of 3 pure forwards. Always think it is a big mistake to change the system that has worked well and got you that far in an effort to out think an opponent.
IMHO, This was one where Messi was simply playing at his best and when he does, then it is all over.
Messi can be overrated (as can all Messiahs) as he has some stretches of play that are really bleh but there is NO ONE that matches his peak when he is on.
And what he did to Liverpool considering how good they have been is insane.
There have been times it looked like the age/beaten up body combo might rob him of some pace but ... yea ... if so it was temporary.