After blackballing Colin Kaepernick and doing everything possible to make those pesky national anthem protests go away, the NFL has since reversed course on their short-sighted policy, and will now encourage and support any matter of peaceful protest.
In addition to the current social climate and some old-fashioned common sense, many believe that a video featuring some of the NFL's biggest stars helped the league decide that allowing peaceful protests was the right move. ESPN's Jason Reid correctly asserts that the presence of Kansas City Chiefs quarterback Patrick Mahomes in that video helped the NFL come to terms with their decision to reverse course.
Mahomes, who has an MVP, a championship and a Super Bowl MVP within his first three years in the league, wields considerable influence due to his play on the field and willingness to speak off of the field. The NFL knew ignoring Mahomes and essentially disrespecting him by not recognizing his opinion as valid would alienate a great chunk of fans from across the league.
Without directly doing so, Mahomes essentially strong-armed the league into saying "Black Lives Matter." How many players in the history of sports do you think can do that?
Mahomes is just a few years out of college and already has influence atop the most profitable sports league to sway the stance and opinions of those running the show. The Mahomes effect can't be understated.