I'm not going to say that Marco Rubio turned in a great debate performance on Saturday, but the tone and volume of the media coverage might lead one to believe that he showed up drunk, kicked over his podium, and screamed that the Old Man of the Mountain got what was coming to him. Sure, Rubio's repetitive recitation of his memorized anti-Obama spiel was a strange and strategically unwise response to Chris Christie's accusation that Rubio was overly dependent on the repetitive recitation of memorized spiel, but the collective press judgment that this mistake could be—and, what is more, rightfully should be—severely damaging to Rubio's entire presidential campaign merely reinforces my view that debates are, on the whole, lousy ways to judge candidates.
But media coverage can have a self-fulfilling dimension, especially in primary elections. The fact that Rubio's public persona, as transmitted by reporters to voters, has turned on a dime from "charismatic savior of the Republican Party" to "out-of-his-depth automaton" (both dramatically exaggerated statements, though in opposite directions) three days before the New Hampshire primary is likely to damage Rubio's popularity among the Republican electorate. At the very least, it will be more difficult for him to sustain the "momentum" that he received from the Iowa caucuses—momentum that itself is principally the product of the highly favorable media interpretation of his third-place finish there.
On the other hand, expectations will be sufficiently lowered for Rubio's performance on Tuesday that if he merely runs a close third once again—and certainly if he does better than that—he will be able to claim a comeback that will likely return positive coverage to his campaign. He also benefits from the lack of a consensus alternative choice for those Republicans who are in the "ABCD" camp (as in, "Anybody But Cruz or Donald"). If Bush, Christie, and Kasich all finish within a few points of each other in New Hampshire, as polls now suggest is very possible, none of these candidates will have the standing to assert strong momentum of their own as the race moves to South Carolina.
Meanwhile, it seems ever more probable that the winner of the New Hampshire Republican presidential primary will be one Donald J. Trump. That this isn't the major story of the weekend tells you all you need to know about what a crazy campaign we're in.