I spoke with Paul Ryan just before 8 AM on election day and I find this story entirely believable. Every candidate talks optimistically on election day, but he was oozing confidence in that interview and it was clearly genuine. I believe they believed they were going to win. And it was compressed because I didn't have their early intel, but Tuesday evening following returns I had the same feeling of dread hit me: they were losing.
And it's not written in the Weekly Standard piece, but I suspect their disbelief was fueled by the same thought as they were having; the country, given a choice, was choosing the Obama way