1) Sebelius gets her butt kicked as she would be a relative unknown and, well, a woman.
Wouldn't the fact that she was a woman help her a great deal? I mean, Obama didn't become famous just because of his 2004 convention speech. The fact that he's the first viable black presidential candidate helped him enormously in terms of media coverage. Why wouldn't the same have happened for Sebelius if she had run instead of Clinton? Sebelius also wouldn't have had all the baggage that HRC has, though of course HRC had enormous advantages as well.