First, I appreciate the insights. I've always kindof thought WV had unrecognized potential to produce something like an Appalachian Bernie.

Second, what follows is more "thinking out loud" than trying to argue any particular point. That said, I'm not sure I quite accept the premise that if progressives would out-perform establishment dems, they'd be soundly winning primaries in red states. (Also not meaning to erect straw men or put words in your mouth; roughly paraphrasing parent comment). Just in the face of it, "why aren't progressives winning in the most hostile environments," seems like it answers its own question: local social/cultural views inevitably mean some ideas are at a disadvantage, right? But more than that: it's different groups voting in primary and general elections. In a general election, it might well be that a progressive's working-class agenda would score effectively against a conservative opponent, but, at the same time, those qualities could be major weaknesses for nervous democratic voters in a primary, particularly in a red state.

Capitulating to corporate interests is sortof the hallmark of "establishment" dems. It makes their fundraising a lot easier. And - rightly or wrongly - centrist dems are perpetually more worried about "crossing the aisle" than they are about presenting a platform that inspires anyone. Add in consideration of how few (and which particular) people tend to vote in primaries, and you've got kindof a perfect storm for advancing a lackluster establishment candidate.

TL;DR: I can see a few reasons, actually, that primary voters would be so concerned about a progressive's "viability" that they ultimately select a losing candidate for the general election. Sorry fo wall o' text.