Menchov was not poor in the Vuelta. Menchov made his typical stupid tactical screw-up in the first week and lost the usual Menchov unnecessary time, meaning that when Cobo was in form on the penultimate weekend, Menchov was domestiquing for the Cantabrian rather than vice versa. Menchov was not untroubled on Anglirú, but he was comfortable for his high finish. Until July 23, 2011, I would have said that he had a better palmarès than Cadel Evans.
The route for the Tour gives Menchov a chance he'll probably never have again, a realistic last shot at completing the GT grand slam, and if Katyusha can surround him with a good team rather than going for the gimmicky all-Russian lineup again, then I don't see any reason why he can't win. There could still be reasons why he won't, of course, though...