NFL ratings were down in the 2017-18 season, continuing a recent trend. What was the cause—the Patriots' continued dominance, anthem protests, growing awareness of concussions? Or was it Donald Trump?

The probable answer: all of the above played a role. As Trump sees it, he deserves credit for the league's dwindling viewership. He says his time in the White House has been more entertaining than the action on the field. "When the NFL's down 20 percent—it's the flag, but it's also the fact that everyone is watching us on the different cable networks," Trump said Wednesday during a rally in North Dakota. "Because frankly, they find this more exciting than the NFL and a hell of a lot more dangerous, right?"

Trump in the fall called for fans to boycott the NFL after numerous players around the league took a knee during the national anthem. TV ratings decreased yet again. They fell 9.7 percent this past season and had dropped 8 percent in the season prior. Still, 14.9 million people tuned in for the average NFL game in 2017. The number in 2016: 16.5 million on average.

In addition to the league's struggles with Trump, its viewership likely suffered because many of its biggest stars suffered injuries.