Sark has a number of things working in his favor here that facilitate the "player-led team" concept.
1- Demonstrated record of improvement (year 1 - year 4) and now success (B12 Championship and playoff berth).
2- Personal story that he embraces, uses to relate to the players and that they can find a way to identify with and connect to.
3- Recruiting success. Replacing good players with good or better players, will build on point 1.
4- Consistency of teaching - low staff turnover, high-caliber replacements when necessary.
5- Consistency of message - He is absolutely right about how key consistency is to building trust.
All of these things create a stable and successful program and allow the culture that he has established to flourish. With that, the natural leaders on the team can emerge and create that "player-led team" concept because they have bought in to his culture and the success that is being enjoyed makes it comfortable for the other players to accept those leaders AS leaders. They are proxies for Sark with the added advantage that they speak in the language that 18-23 year-olds understand. They also bring the added element of peer pressure.