You still got to pick the best players, and it should be the coach' job to deal with the egos and stars and somehow get them to play together. Of course, easier said than done. I think they also lack some play time together, with for instance three players joining just a couple days before the first game because of the NBA finals. And finally, for pretty much all other teams, it's such a pride to play against team USA, they give it all out on the court.
Fouls and refs shouldn't be an excuse, they're all strong and physical players and should be able to adapt very quickly.