An interview I saw with, I think it was Marcus Spears, and he said that at different times the main guys have been a leader. Guys like Romo, Witten, Ware, Bradie James, and Marcus Spears have all been vocal leaders.
I think guys like Ware and Romo need to step up more and take on more of a leadership role. Supposedly, with T.O. out of the way Romo can do that now. I'm not too sure, but I guess we'll see how it plays out during the season.