No wonder alarm bells are sounding in NFL commissioner Roger Goodell’s office.

The league's average TV audience through Week 5 of the 2017 season dropped 7 percent vs. the same period of the 2016 season, according to Nielsen data obtained by Sporting News. Worse for the league, the average game audiences are down 18 percent compared to the first five weeks of the 2015 season.

The NFL's average TV audience (including Sunday afternoon, Sunday night, Monday night and Thursday night games) slid to 15.156 million viewers through Week 5 of the 2017 season. That’s down 7.42 percent from an average of 16.371 million viewers through the same period of the 2016 season, and 18 percent down from the average of 18.438 million viewers through the first five weeks of the 2015 season.

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The "Colin Kaepernick Effect" is one of several possible factors in dampening the NFL's TV numbers. Natural disasters such as Hurricane Irma, increased competition for eyeballs from cable news, the Oct. 1 massacre in Las Vegas and the changing TV habits of younger, cord-cutting viewers have likely taken a toll as well.

There's also the spectacle of President Donald Trump urging football fans to boycott the country's biggest sports league as long as players kneel during the national anthem in protest of racial injustice.

...NFL attendance and ratings are WAY DOWN. Boring games yes, but many stay away because they love our country. League should back U.S. — Donald J. Trump (@realDonaldTrump) September 24, 2017

The NFL remains the gold standard of TV, not just in sports, but all entertaining programming. But the NFL’s drop in audience could set off a chain reaction that won’t be good for the $14 billion league — or the TV partners who pay billions for TV rights.

Partner networks ESPN, CBS Sports, NBC Sports and Fox Sports promise advertisers and sponsors certain audience numbers. If those numbers are not reached, the networks have to cough up so-called "make-goods," or free ads, to advertisers who didn't get their money's worth. There's nothing TV networks hate more.

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Now that player protests appear to be hitting owners, TV networks and corporate sponsors in the pocketbook, it's probably no coincidence Goodell wants all players to stand for the national anthem. The NFL finds itself in a "very volatile and dangerous place," said ESPN Insider Adam Schefter on Thursday's "Mike & Mike" morning show.

"It is very sensitive. It is chipping away at the popularity of the sport," Schefter added. "There are people who are turned off to what’s happening. There are people canceling their DirecTV subscriptions.

"The business of the game, by the way, also affects the players. Because for every dollar that the league is collecting, 48 cents go to the players."

The numbers indicate some fans have discovered there’s more to life than watching the NFL on fall Sundays. The question now is: Can Goodell and the league get them back?

With more than one quarter of the 2017 season in the books, that’s an open question.