For the reasons I laid out on Sunday, the outcome of the Iowa caucus is notoriously hard to predict even in a normal election year, which 2016 is decidedly not. The most reliable poll, according to longtime observers, is the one conducted by the Des Moines Register. This time around, its final poll projected unusually high turnout on the Republican side, with Donald Trump leading the field with 28 percent, followed by Ted Cruz at 23 percent, and Marco Rubio at 15 percent. All other Iowa polls released in the past few weeks had found similar results. Though Cruz began January as the frontrunner for the nomination, at least in the state, his support in the polls was sliding, meaning that Trump had retaken the lead; Rubio, concurrently, was on the rise.

Those trajectories, as I noted Sunday, struck me as plausible. Still, I predicted a different outcome. I wrote that I expected Cruz to win, and added that I wouldn’t be surprised to see Trump underperform—even if turnout was high, which I thought it might well be. In the end, a record number of Iowans voted in the Republican caucus. Cruz won, with 28 percent of the vote. Trump came in second, with 24 percent, and Rubio finished third, with 23 percent.

The reason I thought Cruz would win is simple: I’ve been paying attention to him; I predicted in November that he would beat Trump in Iowa. I’ve been paying attention to Trump; I wrote in August that his support would be broader and more durable than Republicans were then anticipating. And for the past week, I’ve been paying attention to Iowa. On Sunday, I posited the following scenario:

I’ve heard a fair amount of speculation about whether [Trump’s] supporters will turn out; from what I’ve learned this week, I’m more curious about what will happen if they do…His message resonates with Americans who feel that no one has been speaking to them, much less for them. His supporters may well be motivated to turn out to vote. To do so in Iowa, they’ll have to perhaps brave a snow storm to attend a caucus, where—per the state’s longstanding tradition—they’ll be seen, heard, and overwhelmed by the solicitous interest and concern of their neighbors. That may serve as a corrective.

Trump’s support has been durable because the various criticisms levied against him—by his rivals, by the political establishment, and by the media—can be discredited on the basis that they are efforts to discredit him. I realize that’s tautological, but it’s proven effective, because many Americans believe that the powers that be are not concerned with their best interests. What’s unique about the Iowa caucus is that it creates an opportunity for people to talk in person, among themselves, without interference from third parties with dubious motives. The only people with a chance to influence the outcome are the people in the room.

That’s what happened on Monday. I decided to go watch a caucus in Marshalltown, which had been described to me as both a reasonably representative of Iowa writ large, and a place where support for Trump was known to be strong. On the Republican side, caucus-goers hear short speeches on behalf of each candidate, assuming someone volunteers to speak on their behalf. The Cruz campaign had an unusually extensive ground game, with hundreds of volunteers, most of them from Texas, having traveled to Iowa to make calls, knock on doors, and, on caucus night, speak on their candidate’s behalf. Brandon Creighton, the state senator from Conroe, had apparently seen the same potential opportunity that I was wondering about. “I asked them to send me to a tough spot,” he told me at the caucus site, the Lions Club, after the speeches, while the votes were being cast.

To all appearances, the campaign had fulfilled Creighton’s request. Turnout at the site was, everyone agreed, higher than they had ever seen it. The Cruz contingent was visible, but one of his supporters, Jean Hilsabeck, told me that she had expected Trump to win. She knew most of the people in the room, she explained, many of them from church, and knew they had come to the caucus for Trump. And Bob Palmer, the Marshalltown man who spoke for Trump, was apparently an unusually credible observer. Creighton told me, somewhat tensely, that he was known as “the town sage,” and Palmer nodded briskly when I asked him later if that was true. But the results didn’t go his way. All told, 121 people had gone to caucus. Cruz won, with 46 votes, one from a woman who arrived wearing a Trump button. Trump came in second, with 32. But Palmer was sanguine: “I think this is the right process,” he said.

By the time I made it back to Des Moines, the race had been called for Cruz. And the commentariat had started to coalesce around a few conclusions: The polls were wrong. Cruz’s victory was stunning and reflective of his unusually good ground game, and not ultimately all that significant: winners of the Iowa caucus, like Mike Huckabee and Rick Santorum, rarely go on to become the nominee. Trump, in light of his defeat, can no longer be considered invincible, but he gave a surprisingly gracious concession speech, and is still a very strong contender. Rubio’s third-place finish is proof of his momentum. These interpretations were easily predictable. The magic crystal ball that told me what to expect also said that a victory by Cruz or Trump would be dismissed, on the basis that the Iowa caucus is weird and idiosyncratic, and that any outcome at all for Rubio would be interpreted in a favorable light.

My takeaways are as follows. The Iowa polls weren’t wrong, exactly. They just had no way of accounting for developments at the actual caucus. Cruz won the Iowa caucus because he, his staff, and his volunteers have been planning for months, and had an unusual presence at the caucus itself. Since the effort was so palpable, some people seem to be interpreting the victory as engineered or artificial. What they’re failing to perceive is that such an effort reinforced Cruz’s claim that he will work for the people. Trump has been making the same claim, and a lot of people believe him. But in Iowa, at least, Cruz had a chance to show the people that he meant it. That’s what clinched the caucus.

As for Trump, his speech was gracious because the idiosyncrasies of the Iowa’s caucus process allow him to dismiss the results as inherently anomalous. And Rubio, I realize, can do no wrong. But Trump remains the frontrunner in national polls. Any Republican who wants to win the nomination is going to have to convince some of his supporters to change their minds. Rubio may be able to do so. But thus far, Cruz is the only one who’s proven that he can.