The problem with Arsenal is that they're one of the best teams with the ball, but relatively poor without it. It's not surprising that Barca covered so much more ground than them, because Arsenal just don't like to get stuck in. They don't relish that part of the game. And until they learn to do that, they'll always come up a bit short.
We would have spoiled the fuck out of that game, call it 'anti-football' or whatever - it is just about the only way of beating, or at the very least, holding, Barca on their own patch. That's why Barca's dominance (and to some extent, Arsenal's) doesn't always translate to results. They don't like to participate in ugly football games.