Detroit Lions secondary coach Tim Walton may not have accepted an offer for a job with the St. Louis Rams, but Lions defensive assistant Brandon Fisher did, according to Dave Birkett. The specific position Fisher will have in St. Louis is unknown right now, but it doesn't really matter. The reason Fisher is leaving Detroit is because the opportunity to coach with his father presented itself, and I can't blame him for taking it after what happened in Tennessee a year ago.
Last year, Jeff Fisher tried to hire his son as an assistant with the Tennessee Titans. When owner Bud Adams balked because of the team’s nepotism policy, Fisher and the Titans parted ways after 17 seasons.
A big reason why Brandon Fisher landed a job with the Lions likely revolved around Jim Schwartz's connection to Jeff Fisher. Schwartz was Fisher's defensive coordinator in Tennessee before being hired by the Lions, and just as Bill Belichick did with Schwartz in the 90s, Schwartz gave Brandon Fisher an opportunity to step into the world of coaching in the NFL.
As far as I know, Fisher is the only departure from the Lions' coaching staff this offseason. All of the coordinators and position coaches are slated to return next season.