Biden's never had a good debate this whole cycle. He's fumbled them at best. What's to make this one after he already won any different? There isn't a chance in hell Bernie wins this no matter what happens on Sunday, and I think, from his speech, that he knows that.
Exactly, though. Biden hasn't performed well in the debates. He was far from frontrunner for most of the primary once voting actually started. Has he ACTUALLY campaigned better than Bernie? Bernie isn't perfect, but it seems as though Biden's campaign wasn't hot shit until AFTER the moderates dropped out and tossed their hats in with him just in time for Super Tuesday. That, coupled with the base's fear of another 4 years of Trump and seemingly thinking Biden is the "safe" candidate.
All lends not to Biden actually putting in the quality work to campaign and debate and make the argument, for himself, that he is the best candidate for the job.
Look, if Biden is the nom (which it looks like he will be) I'll be voting for him 100%. I'm not a Bernie or Buster, never have been, and I think that is a terrible stance to take as a voter if you are. But I defintiely do not think Biden actually campaigned or debated better than Bernie to get here. So let Bernie stay in and debate him.
If Bernie wrecks him in the debate, maybe Biden ISN'T the strongest candidate to take on Trump in 2020 afterall.