He had good reason to be shocked. Bennett is reliably conservative with considerable seniority. He's also one of Senate Minority Leader Mitch McConnell's right-hand men. In every way, he represented the establishment within the GOP. And, ultimately, that's why he lost.
His gravest sins, according to critics, were his longtime support for a health insurance mandate and his vote for the TARP bailout of the banks.
Inside the Beltway, the shock is even more profound. Most of the news stories describe Bennett as being "ousted" or "kicked out" of the GOP, as if he didn't lose the contest fair and square. The pundits' descriptions are even more stark. "A guy like Bob Bennett, who is a right-wing conservative, is being driven out because he's not sufficiently conservative?" asked an incredulous Juan Wiliams on Fox News. "If I lived in Utah, I'm going to give up Bob Bennett and his seniority and connections?"
On "Meet the Press," New York Times columnist David Brooks fumed, "This is a damn outrage." The Washington Post's E.J. Dionne Jr. lamented, "It's almost a nonviolent coup." Presumably he meant it was almost a coup, not almost nonviolent. Regardless, it's a curious way to describe a perfectly peaceful democratic process.
The conventional Beltway interpretation is that Bennett fell victim to the growing right-wing "extremism" of the Republican Party, fueled by those Huns, the "tea partiers."
This is not an altogether crazy interpretation, but it is an insufficient one. It assumes that those who voted him out at the state GOP convention were irrational ideologues who cannot grasp their own interests.
Another way of looking at this is that the GOP rank and file are actually serious about what they say and don't use the same scorecard as Beltway denizens.
The delegates understood, better than most, that the other Republican contenders will almost surely win in November. (Utah hasn't elected a Democratic senator since 1958.) So, the GOP wasn't risking losing its Senate seat, only Bennett's "seniority and connections." That's no small thing, but it is hardly calamitous either (particularly given the clout of Orrin Hatch, Utah's senior senator).