I don't understand the Biden pick. If he wanted someone with foreign policy credentials, he should've picked Sam Nunn. I think Kerry should've picked him, too.
Nunn's symbolism as a homophobe would have hurt Obama in some circles/blogospheres while Biden was a neutral, calming choice. Ultimately the best VP is one that doesn't ruffle any feathers - since it's pretty rare for a VP to deliver a significant positive. The more you hear about a VP pick, the more trouble that VP pick is getting into.
Biden did a good job by only breaking into the news cycle one or two times.