Actually, it's athletes who generally have the advantage. If you look at past winners, athletes comprise the largest % of winners. Generally, they are physically co-ordinated and know how to train and compete. If they have any sense of rythym, they are in the finale. I think Clyde Drexler probably had the most difficulty due to his extreme height and his partner's petiteness - I don't think they have basketball players fill the athlete niche anymore.
Sabrina and Kyle are both in the wild card category as related to participating. I'd rather see either one of them before Carson. The 2 of them can dance. Carson's comic, but not the best dancer of the 3.
I didn't mean a physical advantage. I think football players have a fan base advantage. They're physically coordinated and know how to train and compete, as you say. But often they're less graceful than other contestants. What puts them over the top again and again is fan votes. Someone like Apolo Ohno isn't that well known outside of fans of that sport, so it's more of an uphill battle for an athlete in an obscure sport to get voters to choose him/her over some other contestant. Football players are known by everyone. That's more what I meant.