I am sure they had an idea who the best ones were and they paired them up with the less skilled guys.
They have "try outs" where all the guys come out and show their skills. Then they get the invite on the show.
Well, any of you that have played competitive sports know that you get those guys who are good in practice, but suck in games. They have the individual skills, but they either can't put them together, they have no mental game, or they simply have no heart.
That's where the elimination fights are good. It separates the fighters from the wannabes. It weeds out your Blake Bowmans like we was on TUF 6. It also helps out those guys who kind of fly under the radar, but show up for the big game.