With Donald Trump skipping the debate to consort with Mike Huckabee and Rick Santorum (because he cares so very much about veterans), Ted Cruz had a golden opportunity to make a strong closing pitch to Iowa voters. He missed it.

Cruz started out strong, with a clever line about Trump’s patois. But after that he failed to hammer home the difference between himself and Trump. Instead, he was dragged into debates about foreign policy and budget bills and immigration poison pills. Maybe Iowa voters will absorb the contrast—that Cruz has a grasp of policy and Trump doesn't implicitly. But maybe not.

As a tactical matter, it wasn't a bad performance from Cruz. He held his own against the other six candidates on stage. His ethanol answer—which at this point has been honed to a razor edge—was exceptionally good. And he probably helped himself more than a little in his long exchange with Rubio on immigration. But as a strategic matter, what Cruz wanted to do was to present himself as a commanding, steady figure. Instead, he got steamrolled by Chris Wallace in the first half and then found himself arguing with Rand Paul—currently at 3.9 percent in the RealClear Iowa average—over who was the more genuine libertarian. That's not the fight Cruz needs to be having four days before the caucus.

But it wasn't just Cruz who failed to take the lumber to Trump—no one at the debate rose to the task. Partly that's because the Fox crew ran a strange debate: They asked very few questions about the frontrunner; they queued up flip-flop highlight reels for some candidates, but not others; they paid homage to liberal shibboleths like climate change and Kim Davis; they devoted time to silly YouTube question about America's supposed climate of Islamophobia from a Bernie Sanders supporter.

The result was something of a muddle, with none of the candidates prosecuting the case against Trump. Instead, they all acted as if they were in an interregnum which had nothing to do with the campaign both behind it and in front of it. It's as if they thought that because Trump was gone for a night, he was vanquished from the field. This seems like a terrible miscalculation.

Perhaps the strangest moment in this strange debate was when Jeb Bush launched an attack on Rubio over immigration. Bush's complaint was that Rubio wasn't a staunch enough supporter of amnesty. Bush caviled that when it really came time to press on for amnesty in 2009, Rubio "cut and run." As always, Bush's political instincts were amazing: He managed to back Rubio into the only possible immigration argument that Rubio could win.