He actually didn't. I watched the entire debate. Yes, the Medicare stumble was a bad one. He couldn't break through the stutter. But, it's the one point in the debate the media keeps replaying. For the rest, it was his usually stutter and pauses (maybe they were a bit longer), and he sounded tired and hoarse. But, he answered every question asked of him.

Biden also appeared to be frustrated and angered by Trump — we know Trump irritates the hell out of Biden (us too)! CNN's journalistic malpractice of letting Trump never answer the questions and lie unchallenged for 90 fucking minutes probably added to the frustration and anger. But, you scarcely hear anything about that.