Two days after secondary coach Tim Walton left to become defensive coordinator of the St. Louis Rams, the Detroit Lions promoted Marcus Robertson to take Walton's place. Robertson was the Lions' assistant secondary coach last year, after spending the previous five seasons with the Tennessee Titans. He played 12 years in the NFL as a safety, mostly with the Houston Oilers before they moved to Tennessee. He finished with the Seattle Seahawks. The Lions have lost five assistant coaches after a disappointing 4-12 season. Walton's new job came one year after the Rams tried to hire him as their defensive backs coach; receivers coach Shawn Jefferson, offensive line coach George Yarno and running backs coach Sam Gash were not retained after their contracts expired; and special teams coordinator Danny Crossman left to take the same position with his good friend new Buffalo Bills coach Doug Marrone.