At FiveThirtyEight, the veteran election analyst David Wasserman essays a comprehensive, okay-now-we-can-forget-about-it take on why Eric Cantor lost his primary on June 10. He offers seven factors, several of which others have promoted, such as the fatuity of running ads calling the Catholic Calvinist Libertarian Dave Brat a “liberal college professor,” which only boosted the challenger’s name ID without making a credible dent in his wingnut armor. He also defends an earlier suggestion that Cantor was culturally out-of-touch with his heavily evangelical Christian primary electorate against claims he was accusing Brat’s voters of anti-Semitism.

But the most interesting data Wasserman provides is in support of the argument that this cycle’s anti-incumbent sentiment is making primary upsets more likely, without necessarily creating any sort of tsunami:

Cantor was only the second House incumbent to lose a primary this year (the first was Texas Republican Ralph Hall), but the warning signs of discontent were abundant: Plenty of rank-and-file House incumbents had been receiving startlingly low primary vote shares against weak and under-funded opponents, including GOP Reps. Rodney Davis of Illinois, Lee Terry of Nebraska and David Joyce of Ohio. In fact, just a week before Cantor’s defeat and without much fanfare, socially moderate Rep. Leonard Lance of New Jersey received just 54 percent of the Republican primary vote against the same tea party-backed opponent he had taken 61 percent against in 2012.

Overall, 32 House incumbents have taken less than 75 percent of the vote in their primaries so far this year, up from 31 at this point in 2010 and just 12 at this point in 2006. What’s more, 27 of these 32 “underperforming” incumbents have been Republicans.

In other words, while Congress’s unpopularity alone can’t sink any given member in a primary, it has established a higher baseline of distrust that challengers can build on when incumbents are otherwise vulnerable. And as the sitting House Majority Leader, Cantor was uniquely susceptible to voters’ frustration with Congress as an institution.

That makes sense. The two underwhelming incumbent GOP performances that struck me earlier in the cycle involved North Carolina’s Renee Ellmers, who won 58% against an underfunded anti-immigration-reform crusader, and Nebraska’s Lee Terry, who did even worse (52%) against a similar opponent.

Now some eager Democrats may look at this phenomenon and predict some general election upsets, and that’s possible. But there’s no real evidence yet that anti-incumbency is trumping partisanship among 2014 voters. And obviously, Democrats have a lot more incumbents being targeted in the key fight for control of the Senate.

Ed Kilgore

Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.