Six years later and it's brought up from the dead? 
But seriously after the results from 2012 and 2016 it does seem that AR and TN were really just waiting on a long term R trend. I mean both states have sizable Black populations, but there looks like a lot of poor White Democrats became increasingly dissatisfied and it prevented a swing towards Obama that could've happened in 2008 or 2012 (to a much lesser extent however) and it accelerated in 2016.
West Virginia is the most clear.
Ironically, even Arkansas swung against Hillary. 
Very good question, and your necro-post actually sheds light and , while also exposing the extremely weak posts on Atlas, as well as the Main Stream medias interpretations of both the '08 Dem Primary, as well as the '08 GE.
Reality is that this is a part of the country where the tradition of Military Service runs deep in the family blood...
As others have noted, it's also a place where Whites vote much more Democratic than in the rest of the former states of the White Supremacist South.
Considering how the older racist folks that grew up in an era where Jim Crow was the law of the land are now dropping off like flies.... I'm still not convinced that the whole argument about "Racist White voters that so many on Atlas were flogging back at the time of the OP makes any sense...
My thought is rather that Obama running as an "Anti War" Democratic didn't play well in these States, considering that they had been shifting heavily Republican since '00, and especially after 9-11.
After all Tennessee almost elected their first Black Senator since Reconstruction not that many years ago, WV obviously still has a Democratic Senator, and after all split from the State of Virginia because of the whole slavery/succession gig during the Civil War....
What do all of these States have in common?
A significant population of aging military vets/families, that have been gradually been shifting "Right" on Social Policy, at the same time that the Democrats have been shifting "Right" on Economic Policy....
