[Yardstick]

I’m going to say the complete opposite. Obama expected a conventional pick from McCain, so he went with Biden to sure up his credibility on foreign policy. McCain pivots by picking Palin and shifts the campaign to reform.

That's what I think it was. That's why McCain kept Palin a secret -- to lure Obama into making an "experience" pick -- i.e. a white guy Washington establishment type.

[YdontUleaveLibs]

I think he picked Biden, because there aren’t very many people that look dumber than 0bama. He is terribly stupid without a written script, even then dumber than bricks. Biden manages to be even dumber. It would be easy for just about anyone else to outshine 0bama, someone like Hillary just shows everyone what a babbling fool he is. So, he picks Biden thinking McCain is still going to pick a middle aged white guy, so in his view Biden was a safe pick.