The difference is, they train throughout the world cup, and the month or more before it, while other players are on a full break, and the other thing being world cup players almost all came back much later to start preseason training. That I really don't agree with, fitness wise, its still a 2-3 week break, and its harder to try and "rush" your fitness training into a smaller space of time. You'll be less well prepared, more injury prone and whats the point of risking the first few games. If Cesc came back two weeks earlier, he'd be less tired, fitter, and able to play, same with RVP.
Lets say both don't hit decent form fitness for 4 games, and we lose the first 3 without them, was a couple weeks holiday worth throwing away 9 points, which could end up the difference between 1st and 5th at the end of the season.
Feel the same way about transfers, if he just went and sorted a keeper and CB< so they could build partnerships and train all preseason they'll simply play better from the start of the season. Save 0.5mil because clubs are hurried and more willing to make a deal on August 31st, but could be 6-9 points lost by then, completely not worth it.
Its not just Wenger though, I can't understand why any club wastes time over transfers and lets players come back so much later. A few days, won't make a real difference, but a few weeks will, no idea why anyone allows it to be honest.
EDIT:- WHY THE **** IS DIABY STARTING. Rosicky played loads in preseason, Diaby hasn't, I don't think, played a single minute in preseason. Rosicky is 10 times the player Diaby is, whose lazy at the best of times, let alone completely not match fit. Rosicky on the wing, Eboue in a more defensive role in midfield. Why play our worst player, with no form, no preseason and isn't good when he's at his best, against a tough team, away, first day of the season. Utter madness.