Warriors manager of basketball analytics Sammy Gelfand has been hired away by the Detroit Pistons, a league source has confirmed with The Chronicle. The Athletic was first to report the news. Gelfand's departure marks the latest setback in what has been a tumultuous week for Golden State's support staff. Within the past three days, Gelfand, head performance therapist Chelsea Lane and director of team security Ralph Walker have left the team. Gelfand, 31, spent five seasons in the Warriors' analytics department. In his role, he oversaw the pre- and postgame statistical reports that have become key assets for Steve Kerr's staff.