Disagree too. JD Heyworth was down about 5 poll points and gaining on McCain in the 2010 primary before Palin put the knife in his back. Not saying 100% we would have unseated McCain, but the chances were pretty decent.
JD was, IMO, the best chance we had, going back (and forward) a few election cycles (Kelli Ward was the later chance, but she's a Chemtrails Conspiracist who's taking another run at Flake's seat now, and if she wins the primary will crash on the shoals this November against the Rat). JD had developed some serious flaws in the years since he lost his reelection to the House, and I thought he had plateaued at that -5% number. I voted for JD anyway, because I had met him a couple of times and liked him personally (well, as much as I can any politician, which is not a whole lot).
There is a perception Palin did him in, but I just don't see the numbers to support that. JMHO.