Some are starting to ask if this is really about nationalism or a personal vendetta.
Donald Trump's attack on the National Football League Friday might have seem to come out of nowhere to some fans, but in reality, his disgruntlement with the NFL has a long history.
Trump, in a three-minute tirade, encouraged owners to fire players who kneel during the U.S. national anthem. The comments resulted in dozens of additional players taking a knee during the anthem, a closing of the ranks among NFL owners to stand against Trump's remarks, and some teams not coming out onto the field for the anthem at all.
Here's a history of Trump's decades-long series of battles with the NFL......
http://fortune.com/2017/09/25/donald-trump-attack-nfl/