West Virginia has always been a heavily unionized and protectionist state. Sam reason why he won such a huge upset in Michigan, despite being behind by as much as 40 percent in some polls.
Lots of voters in the primary who were Trump supporters and socially conservative democrats voted for Bernie because they found out they were registered democrats and couldn't vote in the GOP primary but decided they wanted to make a message by voting for Bernie.
I'd say it's somewhat of a mixture of the above, some of it being strictly protest & some of it being a positive response to his populist straight talk.
