Every year, the story of the Super Bowl is partly a story of its gargantuan audience. Of the 20 most-watched TV broadcasts in U.S. history, 19 are Super Bowls. (The other one is the series finale of M*A*S*H.)

But this superlative legacy is in tension with an equal and opposite force: the steady collapse in NFL viewership. The size of the league’s average per-game audience has declined by about 17 percent since 2015, an astonishing fall for the crown jewel of pay TV.

To explain the mystery of cascading football ratings, observers have pointed to several potential culprits. In the autumn of 2016, analysts blamed the election and Donald Trump’s nonstop antics for pulling viewers’ attention from football to the presidential campaigns. Last year, they blamed players’ protests and the president’s relentless tweeting. But now evidence is mounting that the NFL’s problems are deeper than political story lines and social-media distractions.

Quite simply, televised football has a television problem and a football problem. The television problem is prominent yet simple. Fewer people are subscribing to pay TV, which means that ratings are declining for just about everything on cable and broadcast. To pick an example quite different from football: The audience for last weekend’s Grammys telecast declined by nearly 10 million, a stunning 30 percent drop in one year that is related to the fact that cord-cutting is accelerating, leaving fewer people (especially young people) with access to cable TV. Attention has shifted from pay TV to mobile devices, which aggregate football highlights, stats, and fantasy scores, allowing more fans to closely follow the sport without actually watching it live on television.

The football problem, though, is more complicated, in part because there are so many fan conjectures and politically motivated conspiracy theories competing for explanatory power. Are viewers turning away from football because of concussions? Players’ protests? Donald Trump’s poisoning the league with political tweets? Players having too much fun? Players not having enough fun? There isn’t much hard evidence to prove any of these hypotheses correct.

Instead there is evidence, sometimes circumstantial and often crystal clear, that football has suffered as its most popular players and teams have disappointed, in various ways. NFL ratings peaked several years ago, when some of the greatest quarterbacks in history were in their record-setting primes and most of the league’s most popular teams were competitive.

That’s simply not the case anymore. Many of the most popular and marketable players in the NFL in 2017 are either injured (like Aaron Rodgers, Andrew Luck, and J.J. Watt), playing for mediocre or noncompetitive teams (like Russell Wilson, Von Miller, and Eli Manning), or both (like Odell Beckham Jr.). It ought to concern the league that the remainder is composed mostly of quarterbacks aged 35 and over (Tom Brady, Drew Brees, Ben Roethlisberger). Of the 10 NFL players with the best-selling jerseys, only one made the playoffs without being injured or suspended: Tom Brady.

Compare this sorry picture to the NBA, where 14 of the 15 players with the best-selling jerseys are healthy and active, and 13 are projected to make the playoffs. Basketball telecasts on ESPN and TNT are attracting 15 percent more viewers than last year, even though their average viewership is still just one-tenth the size of Sunday Night Football. The upshot is straightforward: Live sports are blockbuster events that fans attend (either in person or virtually) to watch superheroic performances. When those superheroes are playing, ratings stabilize or rise. When those same players are just wearing sweatpants on the sidelines, ratings drop.

But it’s not just a dearth of star players; the NFL also suffers when its most popular franchises are suffering. This has been particularly clear in the playoffs, which have shown some of the worst ratings declines of the year. An analysis by the media research firm MoffettNathanson ranked the league’s teams by internet traffic to their official websites. Just four of the 13 most popular teams made the playoffs. But of the 10 least popular teams in the league, half of them made the postseason and played in the first round of the playoffs. It will surprise no one that ratings for that week were dismal, down 20 percent from the previous year.


The Most Popular NFL Teams, by Traffic to Their Websites

MoffettNathanson

The implication is straightforward: Ratings dive when the most popular teams take a dive, too. As long as the Dallas Cowboys, Green Bay Packers, or another popular team is playing and winning and throwing touchdown passes all over the place, football audiences are still astronomical and fairly bulletproof. (Indeed, the six most-watched playoff games from last year all involved the No. 2 Packers or No. 4 Steelers.) But when Kansas City plays Tennessee in the first round of the playoffs, ratings plummet. By this analysis, Tom Brady’s Super Bowl–clinching comeback against the unheralded Jacksonville Jaguars may have saved NBC and its advertisers tens of millions of dollars’ worth of captive attention.

And this is precisely why the decline and fall of the NFL is such a big deal for television—and, truly, for much of the retail industry. Television is a $70 billion advertising business, and the NFL is its keystone. The Super Bowl is by far the largest live broadcast event in the U.S. Football accounts for almost half of Fox’s “gross ratings points” (a common proxy in the ad industry for audience reach) and at least one-eighth of the same measure for CBS, NBC, and ESPN. Its demise will encourage more large media companies to merge—as Disney and Fox have proposed and CBS is allegedly discussing—and nudge even more commercial dollars to internet advertising companies, where Google and Facebook stand to benefit. Football’s rise to cultural dominance mirrored the ascent of pay TV as the single best business model in American entertainment history. Today, both industries are falling back to earth together.