They may represent a significant slice of Vox Populi, but they aren’t on heavy rotation in most newsrooms. Conservative talk radio blows a whistle that many journalists either can’t hear or don’t want to listen to. The same goes for Breitbart.com, which sent a reporter to Mr. Cantor’s district. He stayed there because he noticed something the polls did not — that Mr. Cantor was seldom seen during the race.

Mr. Brat gave an interview to Mr. Beck. Mr. Levin got on the Brat bus early and stayed there, and Ms. Ingraham went to his district and spoke on his behalf at a well-attended event.

At some point, Mr. Cantor and his staff must have realized that the race was not the cakewalk they thought it was, and they put out silly attack ads suggesting Mr. Brat was some kind of closet liberal. The voters who pushed him past Mr. Cantor by a margin of 11 points knew better, suggesting that paid news media will never trump the unpaid sparkle that Ms. Ingraham and her conservative cohort conveyed.

Even a cynical power broker like Frank Underwood on “House of Cards” — also part of the House leadership — knew that if you don’t pay fealty to the voters who elected you, all the trappings of leadership can disappear at the whim of the people.

Once the smoke dissipated last week and it was clear that a primary result involving only 65,000 voters was going to remake the House leadership, embolden the Tea Party and, perhaps, derail immigration legislation, the Beltway media apparatus whirred to life to crawl through the wreckage. The Washington Post and The New York Times did dozens of autopsies in the aftermath, while Politico commissioned over 60 articles and counting. (It did run a smart piece in the spring suggesting all was not well in the home district of the House majority leader.)

Jim McConnell kind of saw it coming. As a staff reporter at The Chesterfield Observer, a large weekly that serves the suburbs of Richmond, he wrote several articles in the spring suggesting Mr. Cantor was in for a fight. And on June 4, he suggested that “Brat’s campaign is gathering steam as it hurtles toward the finish line.”

“You could tell wherever you went that Cantor was incredibly unpopular, that people saw him as arrogant,” he said in a phone call on Friday. “Dave Brat gave me his cellphone number when I first met with him, and I pretty much had him to myself.”