I think Jonathan Cohn is basically right about this:
Let's stipulate that these instant polls are not the most accurate measures of public opinion. Here's the interesting thing: The results are virtually identical to the results from last week's debate between Barack Obama and John McCain. In CNN's poll, 51 percent thought Obama won while 38 percent thought McCain won. CBS had it 39-25 for Obama.
... Obama and Biden don't really have similar personalities or debating styles; their backgrounds are pretty different, too. The same goes for the Republican ticket is even more disjointed. McCain and Palin are as different as two candidates can be. But when paired off against their counterparts, both the presidential and vice presidential candidates performed at basically the same level.
It could be coincidence. Or it could be the fact that they made the same essential arguments--and the viewers reached the same conclusions about them..
In the Couric interview, Palin mangled her talking points so badly that all anybody noticed noticed was the mangling itself; the points themselves receded into the background. Her much-improved performance last night, though, had the paradoxical effect of throwing the weakness of the GOP message in this election cycle into sharper relief. To my mind, one of the more telling moments in the debate came when Palin, unbidden, latched on to a Biden reference to education, and started talking about all the teachers in her family, and how her kids attend public school, and then did her shout-out to her brother's third grade class - all of which would have been an ideal anecdotal way to lead into a more substantive argument about education policy. The fact that Palin didn't really have a substantive point (beyond vague references to paying teachers more and making NCLB more flexible) can be attributed in part to her lack of knowledge on the subject, no doubt, and perhaps to her lack of interest in policy detail - but it also reflects the fact that the McCain campaign hasn't put any energy into developing a clear, consistent, and popular message on education. Now, there's nothing wrong with that in principle: McCain wants to toe the line on the federal role in education, so he's mainly proposed small-bore initiatives and made notional commitments to school choice; fair enough. But when you don't have much to say to the middle class on taxes, either, and when you haven't figured out a way to address the liberal critique of your health care plan, and when you don't want to talk about immigration at all (except out of the side of your mouth, to Hispanic groups), when you have next to nothing to say about crime or poverty or the country's infrastructure or any other domestic issue except drilling and earmarks ... well, it gets real tough out there real quick, no matter how many times you throw around the word "maverick."