So if Barca lacked 4 of their best and most decisive players, they'd be in no worse state than what they were before?
Lets see, Chiellini is out which means pull Mascherano out of their starting 11, rendering their central defense to consist of Piquet + X
Their equivalent of Marchisio is Iniesta, so take him out of the starting 11 aswell. Now, remove their usual go to guy to cover the holes in defense, as well as one of their most regular starters in midfield, Busquets (Asamoah). Then remove their best attacking player, the guy who makes it all run in attack, Messi (Vucinic).
That's one sorry Barca team that's left. They'd struggle, just as we are struggling.