NEW YORK — The biggest of stars is off to a slow start this season.
"American Idol," that reliable ratings juggernaut, had a drop in viewership of more than 15 percent for its first two episodes back, underscoring how rough it is to attract and keep a devoted following when there are so many entertainment options.
Not so for the NFL.
Last month, its conference championship games were the most watched in 30 years, and it soars into Sunday's Super Bowl defying the ratings drag that plague much of TV.
"Every once in a while on TV, these events galvanize the nation, like 'Who shot J.R.?'" said Kelly Kahl, the senior executive vice president for CBS Primetime. "These things come along once every five, 10 years. The Super Bowl is every year."
In 2006, NFL games on CBS, Fox and NBC averaged 16.3 million viewers. By 2011, that number had climbed to 19.8 million (down slightly from 20 million a year ago). Looking at the prime-time lineups on the Big 4 broadcast networks — the traditional home of mainstream entertainment — puts into perspective how unusual that surge is.
In 2006, their prime-time shows averaged 9.8 million viewers during the NFL regular season. Five years later, that had decreased to 8.1 million. The NFL's advantage had multiplied from 66 percent to 144 percent.
"It's gotten great momentum, and nothing has gotten in the way to stop that momentum," Kahl said.
A close score Sunday between the New England Patriots and New York Giants likely will break the record set by last year's Super Bowl for the largest audience in U.S. television history of 111 million people. That's not to be confused with the highest-rated show ever, measured by the percentage of all American homes with TVs tuned into a program. The "MASH" series finale, watched by more than 60 percent, still holds that distinction.
Population growth partly explains last year's big number, but massive interest in the game also does. At 46 percent, the 2011 game compared favorably to the Super Bowl record of 49.1 set in 1982 during the golden age of TV watching.
Network executives can rattle off all the reasons for the NFL's appeal: Scarcity of games, winner-take-all nature of the playoffs, fantasy football and gambling, the unpredictability of sports, the stunning visual of the NFL in HD.
The formula is not a secret, but replicating it is mystifying.
"The answer is elusive," said ESPN executive vice president John Wildhack. "If people knew, then others would emulate it."
It shouldn't come as a surprise that the TV property outside of sports most similar to the NFL is probably "Idol."
What those competition reality shows can't match is the singing contest equivalent of the "Madden" video games, said Brad Adgate, an analyst at Horizon Media.
"There might be some fantasy league for 'American Idol' or 'Dancing With the Stars,' but there's not anything as remotely near popular as for sports," he said.
College football is surging in popularity, too, and the two sports build off each other. The fame of college stars boosts interest in the draft, keeping the NFL in fans' consciousness during the offseason. Those players arrive in the pros already with a following.
Unlike other sports' championships, the Super Bowl has proved remarkably consistent at drawing big audiences even when small-market, tradition-poor franchises make it. Still, the NFL has been on a fortuitous run in recent years of close games and intriguing story lines.
The last four Super Bowls have featured a New York team (the Giants in 2008), an undefeated club (the Patriots that year), two appearances by the vaunted Steelers franchise, one by the vaunted Packers franchise (against Pittsburgh last year), and the feel-good tale of the Saints representing hurricane-ravaged New Orleans.
And after a brief stretch when it appeared a team didn't need a superstar quarterback to win (Brad Johnson, Trent Dilfer), the glamour has fully returned to the position. With Tom Brady and Eli Manning, this year's Super Bowl features a supermodel wife and the first family of QBs.
It's been a good year for TV sports ratings in general with the World Series and Stanley Cup finals going to a Game 7 and the NBA needing six games. But those sports always risk a sweep and the lower ratings that generally follow.
NBC's Bob Costas, who will host the network's Super Bowl coverage, is unabashedly a bigger fan of baseball than any other sport. He can rave about the appeal of the NFL's one-and-done model — but he would never want MLB to cut down to a three-game series.
"What's best for baseball television-wise works against it as far as the integrity of the competition," he said.
And so the NFL will remain a singular entertainment property bigger than just a sport or TV show.
Of this Sunday, Wildhack said, "It's an unofficial national holiday."
Follow Rachel Cohen at https://twitter.com/RachelCohenAP.