These articles are from a couple of years ago, things have somehow gotten worse since then...

http://bleacherreport.com/articles/2584463-where-are-all-the-black-nba-coaches-examining-a-sudden-silent-disappearance

https://www.sbnation.com/nba/2014/5/16/5723170/nba-race-problem-coaches-gms-owners

There have been 3 head coaches fired this season. All 3 of them were black.

1 was fired 3 games into the season. 1 was fired 19 games into the season after making the playoffs in his first season. 1 was fired 45 games into the season with his team 1 game over .500.