Oakland Raiders defensive coordinator John Marshall will not be back with the team, Vittorio Tafur of the San Francisco Chronicle reports.

In two years under Marshall, the Raiders ranked 26th (2009) and 11th (2010) in total defense. Though the defense improved its overall ranking, the Raiders' run defense ranked 29th in both seasons, allowing over 175 rushing yards in five games this season, including three 200+ yard games, all of which resulted in Raiders' losses.

Oakland's pass defense ranked 2nd, but allowed 29 touchdowns.

The 65-year old Marshall has 31 years of NFL coaching experience, including 13 as a defensive coordinator with the Atlanta Falcons (1983-85), San Francisco 49ers (1997-98), Carolina Panthers (1999-2001), Seattle Seahawks (2006-08) and the last two seasons in Oakland.

Who replaces Marshall in Oakland is unknown.

Raiders owner Al Davis is not averse to taking an unorthodox approach to his coaching staff, and a new defensive coordinator could conceivably be in place before a head coach is named.

The Raiders are the only NFL team without a head coach, though offensive coordinator Hue Jackson the favorite to ascend to the position.