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.

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.