What is the Deal with Biden?

I've defended the guy here more than once, and I know he means well and is trying hard, but some of the stuff he says.. hoo boy. This time, he criticized his own ticket's ads in an interview with Katie Couric.

Is he really this bad at controlling his mouth? I dunno, but if he is, he needs to be slapped upside the head a bit. His behavior of late has been so odd that it keeps reminding me of my still-not-forgotten Hillary Screen Pass Theory. :)