I would suggest it's a disqualifier when the loser is one who has already held the seat, and then gets tossed out by his constituents by such a wide margin.
As opposed to a guy who couldn’t even win a Primary. He was creamed in it BTW. If you didn’t know, ‘06 was a bloodbath for the GOP, especially in Blue states. Santorum won twice in PA running as an unflinching Conservative both times. That is a remarkable feat.