The two are in many ways remarkably similar. Each is trying to become his party’s presidential nominee, and each is tapping into the anger and resentment of voters who feel they’re being cheated by a class of people who are denying them the secure jobs and rising living standard they’ve earned. Voters who think the source of their pain is in Washington vote for Trump, and those who think it’s on Wall Street vote for Sanders. Further, both candidates are performing the same, drawing around 35% to 40% support on average, with a few higher or lower exceptions.

And yet – one is the political phenomenon of the age, front page news every day, and looking ever more like his party’s nominee. The other looks like one of those curiosities who occur in every cycle, whose flame flares brightly but briefly, and who will be remembered in a year as a footnote, if at all.

So what’s the difference? The answer is obvious: Trump faces four opponents who split their support, so his 35% makes him the winner, while Sanders faces only one opponent, so the same share of the vote (his average vote share actually beat Trump’s on Super Tuesday) makes him a no-hope loser. They’re two politicians who by most measures are doing the same thing and getting the same results, but as the game theorists would say, the structure of the game has led to opposite outcomes.

Many lessons will be drawn from this presidential race, and one of the most important for party leaders, donors, and prospective future candidates will be why so few candidates pursued the Democratic nomination. An anecdote suggests one reason. In April 2008, I was sitting backstage at a conference with two former government officials, both famous, a Republican and a Democrat, old friends; I can’t use their names. The Republican said, “You’re supporting Hillary, right?” “Yes,” said the Democrat. His friend asked, “Why?” The Democrat replied, “Because I don’t want my car to blow up.”

We’ll presume he was speaking metaphorically. The presumption that the Clintons, in addition to being formidable fund raisers, are tough, take-no-prisoners operators had intimidated a guy who was known as a pretty tough customer himself. More broadly, Hillary Clinton prevented any credible challenger from entering the race by creating an air of invincibility that took many years to build. When Sanders unexpectedly surged, the dearth of other challengers made all the difference.

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The lessons are not self-evident. Advising future candidates to recreate Hillary Clinton’s situation is not especially useful unless they can start working on it in college, as she did. Party leaders and donors used to exert powerful influence over which candidates got a foothold, but in the age of social media and online fund raising, that power is waning.

It’s safe to guess that all players will conclude they must start years in advance to influence who brings the most resources into the contest, how delegates are awarded, and when – that is, shaping the structure of the game. And they’ll need to do it long before the next contest is visibly underway.