I can understand why someone would see Biden as a weak candidate, but the idea that he'd do worse than O'Malley or that Republicans have a candidate strong enough to win by ten points is just absurd.
Biden is just the biggest gaffe-machine of them all, even bigger than Schweitzer. Almost everything he says seems to come out wrong. O'Malley on the other hand is always on message. In the past I'd say that both of them have come across as very awkward to me, however, it seems like O'Malley has worked a whole lot on toning down his awkward side lately. The biggest difference however is of course that Biden would have to run on a platform constantly defending everything the Obama administration did. Just like Cheney would have lost in a 20% margin (or more) landslide had he run in 2008, Biden would also be a heavy underdog in 2016. However, O'Malley could do as McCain and run on his own very strong executive record, both in Baltimore and greater Maryland. O'Malley has done what very few other Democratic governors or leaders have done for the past decade; actually implementing almost the entire Democratic platform in his state. From 10.10 dollar minimum wage to being among the first to implement same-sex marriage to innovation of the economy and educational standards to a very successful battle against organized crime in Baltimore to so many other major reforms. He's simply been extremely effective. Effectiveness should count for something as well, even if you're not the single person best fitted to win over viewers on Oprah or other talkshows.