Bernie Sanders has accomplished something remarkable and completely unexpected. A year ago today, Hillary Clinton led Sanders by 55 points in the Real Clear Politics national polling average. Now, he trails by only 7 points on that same index — and in three polls over the past two months, he has tied or led Clinton nationally. He has reshaped the conversation in the Democratic race and, despite Clinton’s assertions to the contrary, pulled Clinton to the left to meet him. And he’s stuck around thanks to a fundraising engine that is surpassing Clinton’s and reaching a far wider group of donors.

Sanders made all of these points during his victory speech on Tuesday night, shortly after TV networks and the Associated Press called the state of Wisconsin for him. That victory got rolled into the points above to present a theme: Momentum. Sanders has momentum, Sanders said. His campaign is what momentum looks like. And that momentum, he suggested, will carry him to victory.

Between the first and the second paragraphs above, we moved from objective to subjective analysis of what’s happening in the Democratic race.

It looks like Sanders will end up winning Wisconsin by at least 10 points. It’s a smaller margin than his last few victories, but it’s larger than RCP's average and any recent polls. The win means he’ll win somewhere in the neighborhood of 20 more delegates than Hillary Clinton — one of his bigger net delegate gains of the primary season.

The recipe he used is the recipe he’s used elsewhere: beat Clinton with white voters enough to offset her strength with black voters. He was aided by Wisconsin having a relatively small black population — a population that preliminary exit polls reported by CNN suggest gave Clinton 7 of every 10 votes. Clinton and Sanders appear to have tied with Democrats, but Sanders won 7 in 10 independents, a group that made up nearly 30 percent of the electorate. So: Sanders wins.

He was supposed to. Those demographics suggested that he would. After Super Tuesday, a night in which Hillary Clinton vastly expanded her delegate lead, FiveThirtyEight outlined the odds of a Sanders victory in each of the next eight states. In seven of the eight, the demographics and past primary results suggested, Sanders would win. He’s won six of the seven that have voted. In most cases, it seemed like he’d win by wide margins. He did.

Is that momentum? Sanders and his advocates say that it is. Others have pointed out how uncommon it is for a front-runner to lose so many races so late in the process, though a top former staffer for President Obama notes that it also happened in 2008. National polling suggests that the race has tightened two points since the beginning of March. Does that count? In the eye of the beholder.

We note again that Sanders’s path to victory is now about as cumbersome as Ted Cruz’s. Like Cruz, Sanders has almost no way to get the delegate total he needs before the convention; like Cruz, Sanders is hoping that convention delegates will be moved by his late charge to hand him the nomination if both he and Clinton come up short.

Part of that argument depends on Sanders continuing to charge, which means continuing to win states even as the calendar turns against him. After Wyoming this weekend, Sanders is projected to win two of the next eight Democratic contests, though Pennsylvania may be close. If he loses five of those eight, what happens to that argument?

Sanders, as we’ve repeated frequently and to the consternation of Sanders’s fans, simply can’t make up the delegate deficit against Hillary Clinton. We made this graph to that point last week. It takes a smaller win than Sanders’s in Wisconsin to make up the delegates he bit off tonight — but Clinton doesn’t really need to make those delegates up anyway. Her lead is very, very well padded.

Momentum feels important. It feels important to win states, just as it feels important to string together a number of singles and doubles in an inning even if you’re trailing by 11 runs. It feels like you’re getting somewhere. All of this feels like it’s offering more than it ever should have, that it’s positioning Bernie Sanders to be a candidate in a way that no one ever dreamed — perhaps including Sanders himself.

But here, in the hard math of the Democratic delegate process, in a series of contests where Clinton has still gotten millions more votes than Sanders — that momentum is mostly a mirage. It looks like water, shimmering there in the desert.

It’s not.