[I]f the new polls are accurate, a not insignificant percentage of Americans have switched their votes since last Wednesday—meaning that they, like many journalists, have apparently decided that a few too many “uhs” by Obama on national television should override all the substantive issues facing the country.I don't know what "not insignificant percentage" means to him, but it's worth pointing out just how few people we're talking about. Okay...it's a little hard to do, because the nature of polling makes it really hard to figure out what changes were a result of the debate and which were not; as of now the HuffPollster polling average has Obama's peak lead back on September 21 at 4.1 points and dropping to 2.3 points by October 1 before the October 3 debate. Perhaps that's an artifact of the way they handle the data; perhaps it shows a real pre-debate change (and part of it is the Gallup shift from registered to likely voters, which has nothing to do with anyone changing their mind). But even using the maximum shift (that is, September 21 to now) and ignoring everything else, what it shows is that Barack Obama's support has slipped 1.6 percentage points while Mitt Romney's has improved 2.6 points.
That's a relatively small group! And even there, it's unlikely that very many people "switched their votes." What we're probably seeing is one of two things. Some of it may be people moving from a candidate to undecided or vice-versa (the current Romney plus Obama total adds to just under 93%, with undecided presumably eating up almost all of the rest). The rest? People slipping in and out of likely voter screens.
(Yes, it's possible that there are much larger migrations between the candidates which cancel each other out. Everything we know about voters, and all the evidence from the polls, says that hardly any of that is happening).
I'm not saying that any of that is unimportant -- if it holds, a 4 point shift is big stuff, and if it's all from the debate, it certainly would be a large debate effect. Although note that as of now we have no idea whether it will hold, and very little idea as to how much of it is from the debate -- and even the portion which is from the "debate" may be not because of the debate per se but because of press coverage of the debate.
But hardly anyone is doing what we would think of as changing their mind. Just not happening. Almost everyone who had already decided is staying put. Some people who were on the margins between a candidate and undecided are jumping back and forth over that line depending on when you happen to ask them and what's the last piece of information they heard; many of them are low-interest voters who usually wait until the last few days to start thinking about the election. And some of them are just more or less enthusiastic about voting, which seems entirely reasonable as a reaction to either the debate or the news coverage of the debate.
Nobody, or at least practically nobody, has actually changed their mind because the candidates' demeanor overrides substantive policy positions. Just isn't happening.