This cycle has been dominated by single-issue "conservatives" who gleefully purge and bash one another over minor variations over some principle or other. It has made conservatism look very trivial. Certainly we have stopped being the generators of ideas, and become slogan-slingers. Conservatives really aren't putting out much in the way of thoughtful, practical ideas these days.
And also, conservatives have done very, very little to make a convincing case on just about anything -- whether it's same-sex marriage, or support for the war, or immigration, or pretty much any issue you want to name. They've simply stood around touting their "conservative principles," without explaining why they're good or important.
I think illegal immigration ends up being THE single issue that makes self-described conservatives look most like a group of loons: the over-the-top rhetoric of the "build the wall NOW" crowd has led to those folks crapping their own beds. At least, that's what I would guess is driving the California results.
Interesting imagery. The idea of border security only seems over-the-top to those folks that have grown comfortable with our national decline into a balkanized multi-culti cesspool of "many nations in one". But if you're right, and it's an aversion to border security that has sent Republicans to McCain in droves, then I guess we never really had a chance did we?