Barca, RM, Bayern etc would win because they play with each other every day. If you watch a lot of games you can tell there is a difference in the fluidity of the moves from watching EPL or Champs league to this. Coaching also plays a part as well, no way Hodgson should be coaching a national team and Klinsmann bombed at Munich so the jury is still out so to say.
I'm starting to think the old Ajax youth policy ring pretty true for everywhere. From a youth level all the best players are usually strikers, as you move up in age group you make the group smaller and the strikers that aren't the best get moved back to midfield, and then next age group the team is made smaller again and the worst are moved to defense and so on and so forth. Eventually you're left with the worst at that age group playing defense and goalie which makes sense in a way as you'd have to say the worst players at this WC and for club teams in general is usually the goalie. Amazing goalies are very few and far between as far as I can tell and usually one of the weakest links on any team. Certainly cost Croatia a chance at points in the first game.