While the issue of experience at the top of the ticket is always crucial.
Name one example in US history of a candidate who lost a Presidential election because they weren't experienced enough.
Usually its not because someone lacks experience, so much as it is that the other guy has so much more. As John Ford says though, the issue usually isn't experience per se, so much as readiness. And one could say that both Carter and Bush would have lost had it not been for rather extreme luck, and the major stone hanging around both their necks at the time was a perceived lack of readiness. Had 1976 been a normal year, Carter never woudl of got the nomination, but if he had, Ford would have kicked his ass. Ford's amazing 30 point near comeback should be the stuff of legend even if he did fall short (kinda like the 300 Spartans).