Why couldn't she run against the existing candidates? Debate them and take the slings and arrows?
I could win the US Open if I only had to play the back nine rather than playing all eighteen with the other players.
Sarah isn't one of the "established elites" inside the Republican Party. Her greatest interests are not with party-line politics; they're with people. She took over in Alaska, for instance, and proceeded to unseat or prosecute corrupt politicians ... Murkowski's included.
What she's doing now, along with NBC and Fox News appearances, is supporting Tea Party candidates that will put her in good standing with the right kind of people.