Through Al Davis, Shell is a member of the Sid Gillmancoaching tree. As coach of the Raiders (at the time located in Los Angeles), Shell compiled a record of 54 wins, 38 losses, and was named AFC Coach of the Year in 1990, when the Raiders won the AFC West division with a 12-4 record, and advanced to the AFC championship game in the playoffs, becoming the first African-American coach to lead the team to the Conference Championship game. Al Davis, owner of the Raiders, fired Shell after a 9-7 season in 1994, a move Davis later called "a mistake".
Shell was officially re-hired by the Raiders as head coach on February 11, 2006. After leading the team to its worst record (2 wins, 14 losses) since 1963, Shell was fired for the second time as Head Coach of the Raiders on January 4, 2007. Although the Raiders' defense was one of the best in the league, its anemic offense, along with a season long feud with wide receiver Jerry Porter led to the team's downfall.