The best team leaders lead by example. They let their actions speak. They are humble and they are willing to sacrifice. Most of the time they are one of the better players. But that is not always the case. Sometimes they are simply someone the team respects because of the way they go about their business and the way they treat people. Being vocal is fine if the actions back up the words. But if the actions are speaking your mouth doesn't have to.
I had a kid once that didn't talk much. He was a freaking stud of a player. Gritty hard nosed kid. He could look at a team mate a certain way and they knew exactly what he meant. He set the tone. People followed his lead. I have had kids that wanted to be leaders. But no one was buying. They talked it but they didn't walk it.
The old saying "Actions speak louder than words" rings true to me. Lead by example.