Yep, season one the female soap star won it.Since then every season it has been smaller men with a dance or athletic background.
The first season can be an aberration because I think it didn't have the same attraction for the stars to be on it.
This season they did seem to stack it with women likely to do well and it still didn't work. I think some is demographics for the show. I think a lot of the women who watch are more likely to vote for the cute guy they want to dance with than a woman setting a standard they can't live up to.
To get a woman to win they may need a season without a guy who is charming, cute and with the physical talent to improve enough to make it to the end. Clone Master P and only cast those guys and I think a woman could win.
I also think that the guys have the advantage sometimes with the partners. A lot of people seem to like certain partners and none of the guys have that IT factor enough to carry the duo by themselves like Cheryl or Julianne. I think casting Derek was a shot at getting a guy that people would support the way they do the female professionals.