Begun, the great unraveling has.

Or maybe it’s just an outlier. No other poll I know of, state or national, has had Trump down by as much as eight points to anyone since Trumpmania took off this summer. (Carson led him by seven in one national poll a few weeks ago but that result hasn’t been replicated elsewhere.) That’s the good news for Trump fans. If you want to argue this is a fluke, it isn’t hard to do. And if you don’t, there’s still a reason for hope here: Trump continues to lead Carson, sometimes by wide margins, on key issues that Republican voters care about. The economy? Trump, 41/12. Illegal immigration? Trump, 37/9. Taxes? Trump, 32/13. All of that is good news.

The bad news is … pretty much everything else.

Trump is closer to third place, currently held by Marco Rubio with 13 percent, than he is to first. He’s already in third, behind Carson and Cruz, among tea partiers. Among white born-again evangelicals, a famously key demographic in the GOP Iowa caucus, he’s a very distant second to Carson. And while he’s competitive with Carson among men, he gets creamed among women. Look at various other polls and you’ll usually find a small gender gap for Trump, with men preferring him a bit more than women do, but here it’s wide. Why that is, I’ll leave for you to speculate. The easy analysis is that his wisecrack about Carly Fiorina’s face damaged him more badly with women than everyone expected, but pat explanations rarely well account for something as complicated as voter preferences.

Another key lead for Carson here is on social issues. If it’s true, per Huckabee’s and Santorum’s victories in 2008 and 2012, that Iowa Republicans will ultimately break for a champion on “values,” Trump’s got a big problem.

That’s not a great result for Ted Cruz either, as he’s expecting to eventually win this state by outperforming Carson with evangelicals, but he’s better off than Trump is. When Iowa Republicans are asked whether Carson shares their values, they split 84/12 (among white born-again evangelicals, it’s 87/8). When asked the same question about Trump, they split … 42/52, with white evangelicals splitting 37/56. Carson also crushes Trump on whether each candidate is perceived as honest and trustworthy or not, with Iowa Republicans splitting 89/8 for the former versus just 48/45 for the latter. And it’s those two characteristics — sharing one’s values and trustworthiness — that Republicans in Iowa rate as most important, with 51 percent combined naming one of the two as their key priority. Strong leadership, where Trump is highly rated, rates at just 19 percent. If you’re a Trump naysayer, there’s your smoking gun for why he’s doomed in Iowa. He’s a bad fit with socially conservative caucusgoers and he’s seen, for good reason, as less of an everyman “outsider” than Carson is. If he hasn’t convinced Iowans by now that he’s One Of Us, there’s no reason to think he will. And if he can’t, then it’s hard to see how he wins the state.

In fact, here’s the data when Iowa Republicans are asked whether they absolutely wouldn’t vote for a candidate:

Trump leads the field in this category, ahead of even the remarkably unpopular Jeb Bush among Republicans generally and evangelicals. Bush is the top choice for president among just five percent of Iowans and his favorable rating, a dismal 43/51, is 10 points worse than Trump’s 53/43 rating. (Ben Carson’s is 84/10.) But even Bush doesn’t top Trump among Iowans in the “definitely wouldn’t vote for” metric. Assuming this poll is accurate, Trump’s best hope to squeeze through to a win in the state may be a Ted Cruz surge — not to the top of the polls but to a strong third place. With Carson and Cruz evenly dividing the evangelical vote, there may be room for a narrow Trump victory with, say, 25 percent compared to 22 or 23 apiece for Carson or Cruz. There’s every reason to expect a Cruz surge too: He’s been organizing in the state for two years, he’s got plenty of dough in his treasury, and he’ll have lots of endorsements when the time comes. But that’s a new headache for Trump — what happens if/when Cruz, who’s also a much better fit with Iowa than Trump is, zooms past both him and Carson? And then the ultimate question presents itself: How many losses in the early states would he be willing to absorb before his ego decides that it’s time to bail? If Trump looks headed for certain defeat in Iowa and a tough, close race in New Hampshire circa New Year’s, will he subject himself to a vote? Trump always wins, or so he claims. What happens once it looks like Iowa is set to prove him wrong?

One more point here. It hasn’t gotten much play in poll analyses so far but Ron Brownstein noted yesterday that Trump is doing consistently well with blue-collar Republicans who lack a college degree while the rest of the field is divvying up college-grad Republicans among themselves. That’s sort of true in this Quinnipiac poll and sort of not. Trump’s not the top choice of Republicans without a college degree — he pulls 24 percent versus 31 for Carson — but he does much better with them than he does with college grads, where he takes just 12 percent. Same with his favorable rating. Whereas most candidates tend to be liked or disliked fairly equally among college grads and those without a diploma, Trump is different. He splits 40/56 among those with a college degree and 59/37 among those without. (Jeb Bush, interestingly, is a mirror image, splitting 54/40 among college grads and 36/57 among those without.) That’s something to watch going forward. Can anyone dent Trump’s blue-collar support? If he loses that, he may be done for.