Not that I think early polls are definitive, but one can easily make the case that increased polarization has increased their value. I strongly doubt we're going to be seeing any 20 point swings within a few months in the modern era.
Which is why Hillary Clinton became President in 2008.
I don't get your point. The deep polarization mainly took root with Obama's win in 2008. Just look how many 2007/2008 polls showed McCain winning Kerry states and Hillary winning Bush states.
Unless you're referring to the 20 point swing, which is obviously much different in a primary as opposed to a general...