The McCain campaign's mistake came in the transition to the general election, when they became surrounded by Republican operatives who had learned their trade from Rove. The candidate was lurched from center to right and back, with messaging more tactical than strategic, a tone more sarcastic than substantive. And when the McCain campaign tried to deploy the Rovian techniques he had deplored in years past, they not only failed to stick, they provoked a backlash among the Independent voters who had long been his core constituency.
In effect, John McCain has been defeated by Karl Rove twice—because he's been tarred by the Bush brush and even if McCain pulls off a narrow upset win, his ability to unite the country will be damaged from day one.
Unfortunately, I don't think Republicans will get the message -- whether they'll repudiate Rove or centrists will be seen with Sarah Palin's post-November 4 fortunes.