Well...POTUS is wading into the NFL pool, stating that one of the reasons that the ratings continue to be down in the NFL compared to previous years. While true, there seems to be a false equivalency between the rating and the flag protests started in 2016.
To begin with, all sports leagues would kill to have the NFL ratings, even at its reduced rates:
Okay....great ratings, but in 2015, 43 of the top 50 events were NFL. What is different? Perhaps the quadrennial Summer Olympics? Add in the once in a lifetime World Series between the 2 snakebitten franchises of the Cubs and Indians (until hopefully again this year) would make up the difference.
Are the ratings drops just exclusive to the NFL? No. Let us take a look at the ultrapatriotic, Southern born and bred NASCAR. No flag protests, no controversial statements. How are their ratings doing? Not good: According to the article, "A whopping 22 of 26 Cup Series races this season have posted a decline in ratings and viewership." The first race of the championship in Chicago was the second lowest rating race since 2000. Add the attendance drop over the last decade, and NASCAR is in a world of hurt as well.
How about the other sports? NBA down. MLB mixed (people watch more when their team is good). NHL down in US, up in Canada. In general, all professional sports ratings have seen a decline over the past few years. I don't remember any controversy in these either.
Maybe it is just the professional sports? NCAA football is still strong, NCAA basketball is improving. Is it possible that the professional leagues have priced out the average fan to see games in person, causing more casual fans which results in lower TV viewership? Add to the fact that the NFL is going through a crisis with regards to health of its players after their playing days, or a myriad of other possibilities explained in this article last year.