Joe Biden has never been anyone's idea of a MENSA candidate, but he has a "hey ol' pal, howya doin'?!?!" quality to him that lots of people find appealing, along with 974 teeth, so I expect him to score lots of likeability points in the debate with Paul Ryan. In addition, the vice president has been around since forever and has gained familiarity with the issues through longevity, if not through the application of a coruscating intellect, so I don't expect him to be caught in too many policy gaffes. There are, of course, other gaffes that he might commit, but I assume that the vice president's handlers are going to make sure that he is on a tight leash when it comes to his debate performance. I figure that so long as the vice president doesn't drool all over himself during the debate, he and his camp will count it as a win.
Paul Ryan, by contrast, is very earnest, but also very wonky and professorial, which may not translate well on television. He needs to show some likeability and bonhomie, but he may not be as practiced at this as Biden is. Ryan deals best with fellow policy wonks, but of course, the audience watching the debate is not going to be filled with policy wonks. Rather, it is going to be filled with people who look for a candidate to be affable. And Joe Biden is primed to be affable.
One more thing: The press, having trashed Team Obama in the aftermath of the first debate, is looking to issue a story about how the president's campaign ship has been righted, and how Joe Biden was the one who righted that ship. Don't be in the least bit surprised if that is the line that comes out of Danville in the aftermath of the Ryan-Biden debate.