Tactically speaking, a staunch conservative would not be the optimal choice to face the far left Obama. A moderate centrist is, because Independent moderates decide elections.
McCain is a moderate centrist with years of the label “independent maverick” on him.
You pick the rightward most candidate who is viable. Pretty much always. FR chose to split among those and favored an unviable, underfunded and outstaffed candidate, and that fracturing of support yielded McCain — who it turns out is tactically optimal against an excellent speaker who is a far left wing liberal. McCain will do better against him than a staunch conservative would do — because of the independent moderates being, as always, decisive.
I think McCain will win. The center will once again decide the election — as it always has.
McCain's a flippin' socialist - just not quite to the degree of his opponent.