That nobody saw it coming may be the biggest surprise among the many prompted by Dave Brat's 12-point blowout of House Majority Leader Eric Cantor. The experts didn't see the signs because they had decided beforehand what the outcome would be and then failed to look for any contrary evidence. In other words, as is so often the case in American political commentary, the experts were blinded by a conventional wisdom of their own making.

Conventional wisdom is usually sufficient because relatively few electoral contests are “wave elections” like that of 2010, in which widespread and deep dissatisfaction with incumbents was the defining context for most voters. Thus motivated, they awarded Republicans the party's most comprehensive election victory in 78 years, sweeping offices from one end of the ballot to the other and in every section of the country. Opposition to Obamacare and revulsion over the manner of its passage was the defining context in 2010, accompanied by a gnawing unease with the growing national debt, excessive regulation and impatience with politicians who promise one thing but do another.

What has happened in the four years since has only magnified public disgust with business-as-usual in the nation's capital. Obamacare is still the law despite its chaotic, costly launch and admitted presidential lies. Federal spending, regulation and debt are exploding even as taxes spiral, entitlement programs that protect the elderly and vulnerable move steadily closer to bankruptcy, a swelling tide of desperate women and children immigrants pours across the border and the middle class is steadily squeezed out of existence. Worst of all, nobody in Washington seems to be listening.

In short, the country seems to be falling apart and many Americans are scared because all they get from Washington is empty political rhetoric and partisan bickering. That is why public approval of Congress is in the single digits and growing majorities are concluding that the proverbial American Dream is no longer achievable. The latter view is strongest among 18- to 34-year-olds, the demographic group that has most directly felt the consequences of the stagnant Obama economy, according to CNN Money’s survey.

Under such circumstances, the idea of an invulnerable incumbent politician looks increasingly archaic. That said, voter fear and disgust is spread somewhat unevenly across the country, it is still early in the campaign before most people begin evaluating candidates, and the quality of challengers varies greatly from one contest to another. But when voter worries are focused, as they were in Virginia’s 7th Congressional District, no incumbent politician of either party is immune from being tossed out of office, even when the incumbent is in the Republican leadership and the challenger is an obscure economics professor at Randolph-Macon College.

Prominent GOPers like Cantor are most at risk because they talk the talk of change in Washington. The proportion of Republican and independent voters concluding that it’s all just hot air is growing, so there will be more upsets between now and November. Come January 2015, the new faces and the survivors better find a way to deliver.