NFL television ratings are down significantly. Good! No other sports league needs a fucking slap in the face more. Roger Goodell’s preening conglomerate sails along imperviously, thinking it is bulletproof. It isn’t. So here is the lesson for the NFL in the declining numbers:

Work harder.

Be better.

Quit assuming you’re always going to rule American sports as if it’s a birthright.

The NFL’s ratings show an 11 percent drop. Some of that is the natural drag of declining TV viewing habits across the board, and the changes in the ways we consume.

A ratings downturn does not flatly mean a decline in popularity or interest, because many of us who are as engaged with pro football as ever simply aren’t sitting stuck in front of a TV for hours. More and more of us watch games via our smartphones or other social media. Others of us are content to watch NFL Network’s RedZone and be inundated with scoring highlights from around the league rather than sit through an entire game and endure the annoyance of penalty stoppages and commercials.

The decline mirrors a genuine problem, though. Ratings for traditional Sunday games are holding steady. It’s the prime-time games that are taking a hit, with Thursday Night Football  ratings down 16 percent, Sunday nights off 19 percent and Monday nights down 24 percent.

That suggests a saturation point; too many NFL games. It also suggests bad matchups and shitty games.

You had Jaguars-Titans one Thursday, and the Buccaneers a Thursday game against the Falcons. A recent Sunday night game was a 6-6 tie. Only two of the nine Monday night games have been decided by fewer than 10 points. There are far to many prime-time matchups that have not interested or engaged viewers.

Meanwhile, baseball ratings have been up, driven by interest in the Chicago Cubs. On Sunday night, the Cubs-Indians game beat Cowboys-Eagles head to head by a 15.3 rating to 11.6. Most times in the past, NFL regular-season games routinely drew bigger audiences than World Series games.

Basketball’s early numbers also are encouraging, with opening-week TV ratings 10 percent higher than one year earlier.

Basketball is the hip sport attracting a younger and more diverse demographic, and baseball, though dethroned as America’s sport, reminds it can still put up a good fight — while kingly football takes its punches and is staggered a bit.

Let’s examine why this might be.

A popular theory would blame the NFL’s diminished ratings on presidential politics and the distraction of the Donald Trump/Hillary Clinton circus. No doubt this has been a minor ratings factor, in that one Sunday night game and another on Monday night went directly against two heavily anticipated and massively watched presidential debates.

Others might cite the Kaepernick Effect, the idea that the Colin Kaepernick-led social activism across the NFL including some players not standing for the national anthem has turned off many fans and potential viewers.

“We don’t think that’s a factor and neither do our network partners,” Goodell said recently.

I’d tend to doubt that, too. And yet, a Seton Hall Sports Survey invited 841 adults to say why NFL ratings were down, and vote for as many answers as applied. The No. 1 response, with 56 percent, was players not standing for the national anthem.

“I don’t think there is a single reason. We look at all the factors,” Goodell said recently. “We don’t make excuses. We try to look at what’s causing it and make changes.”

For me it’s a little bit of everything. The general decline of traditional TV viewing. Kaepernick. An election year. Bad games. Too many penalties. Replays. Concussions. A perceived diminished level of play. The rise of RedZone. Oversaturation. The Cubs. Shoot, I might even cite the same-old-same-old of Deflategate-surviving New England being the Super Bowl favorite again. Ho hum.

There might be another reason for the NFL’s struggles, though, of course, and it’s the proverbial elephant in the room: The Ray Rice Effect. The debilitating, cumulative impact of domestic violence and other off-field wrongdoing by too many players.

The more players you find it difficult to respect or like, the less apt you are to love that sport. Or to spend your valuable time watching it.

This league has been cocky for too long in its impenetrable suit of armor. If nothing else, the downturn in TV ratings has forced a refreshingly humbled NFL to work to earn back the trust and the viewers who have left it. This is not a bad thing.