A bit of both - obvious if you play a very strong positional game, the chances of getting scored on are much lower, but sometimes remarkable players do impressive things even with good positional play. Strong positional play ensures that it happens very rarely, but there are times when a player will make a slight mistake, or a great player will do something remarkable that even the best defenders will have trouble dealing with. It's not black and white. At least that's how I think of it.
Sandro was pretty damn close to that yesterday. No player really ever got the best of him and Messi drifted away because of that. No one would blame Sandro if Messi did best him once or twice
