As a society we value the ability to perform in athletics. That being said, our athletes are highly regarded, and respected. So many people look up to them, and respect them. So if they use their fame, and the level of reach they have, they can easily help educate those on BLM, and they can help to bring BLM have more attention.
The black lives matter movement is an important and peaceful movement that encourages people to stop and think about how they treat black people and how black people are treated by the police. This is something that everyone should be a part of and everyone should fight to end racism.
Sports stars are looked upon as role models for young people and they should promote positive messages. Black lives matter movement is trying to focus on improving the racial tensions in our country. Sports stars have an opportunity to do good work but many times the media attention focuses on those stars with bad behavior or the ones who have committed crimes.
Movement for equality and justice have always benefitted from celebrity participation because celebrities can get media attention for issues important to that movement. One example is George Clooney's involvement in stopping the Darfur killings. As more sports stars join Colin Kaepernick is publicly drawing attention to the Black Lives Matter Movement, politicians and the public will see the urgency of the movement's issues.
Sports stars should do what they are paid to do. They are paid to play their sport. The people and organizations that pay their salaries are not paying them to be political activists. The people who pay their salaries want all people to be fans of the teams, not just people with certain political views.