[jimterrapin]

You're correct in some regards, but the model of $=victory is not as consistent as it used to be.

I think of David Brat beating House Speaker Jared Cantor in 2014 as being the canary in the coalmine.

There's never an apples to apples comparison, but Cantor had Brat outraised by over 20 to 1, and Brat beat him. On top of that, campaign messages are more and more delivered and received via free mediums, like YouTube, which brings the cost of a campaign down tremendously.

[maxerickson]

Brat defeated Eric Cantor who was House Majority Leader not Speaker. John Boehner was Speaker.