As he sees it, the problems stem not from the polls but from how the press interprets them. During the long run-up to the 2020 primary season, he saw pundits fall into familiar traps. The same sort of commentators who expected Trump to collapse four years ago have consistently predicted a Joe Biden implosion that, as of this writing, has yet to happen—perhaps in part because Biden’s core supporters, like Trump’s, are members of demographics underrepresented in the press (for Trump, non-college-educated voters and rural voters; for Biden, non-college-educated voters and black voters). Despite Biden’s durable lead, the press has been quick to crown a series of front-runners in waiting, from Kamala Harris to Elizabeth Warren to Pete Buttigieg—all while largely ignoring Biden’s most persistent rival for the top spot in the polls: Bernie Sanders.

To locate story lines where they don’t exist, commentators seize on outlier polls, like the one from Monmouth University in August that suggested a closer race than any previous survey had. (That single snapshot was covered so breathlessly that the director of the university’s polling institute took the rare step of publicly noting how much it deviated from the others.) Or pundits rely instead on what Silver described to me as “stylized facts”: A strong debate performance or fundraising quarter will kick off a round of coverage of a candidate’s supposed surge, even if polls don’t detect much movement. It’s not that these factors don’t matter—they do—but Silver’s work suggests that they don’t matter nearly as much as most journalists imagine. By Silver’s estimation, the average debate performance moves polls about as much as an average week on the trail—and, as Senator Harris can attest, even a well-received moment can take a candidate only so far.

What does this mean for coverage of the general election? Regardless of who emerges as the Democratic nominee, 2020 will have a different complexion from 2016: Trump is now an incumbent, not a curiosity, and his opponent won’t be Hillary Clinton. But a tight race with a polarized electorate offers plenty of chances to repeat common mistakes.

Yascha Mounk: Trump could win again

In Silver’s view, the media were overconfident in a Clinton victory because of long-held assumptions about the mechanics of American politics. Take the “ground game”—the business of identifying voters and getting them to the polls. Some pundits initially argued that if the election was close, Clinton’s superior campaign organization would put her over the top; then, after she lost, many flogged her for failing to get out the vote in key states. Yet decades of political science suggest that such tactics have a relatively minor effect on election results. Based on his analysis of late movement in the race, Silver argues that factors mostly beyond Clinton’s control mattered far more than the success or failure of her canvassers in the Upper Midwest. These factors included Trump’s ability to command the news cycle—Silver has found that earned media is far more valuable than the kind you can buy—and James Comey’s belated reopening of the FBI investigation into Clinton’s use of a private email server, which had a measurable impact on polling.