Oakland also got rid of special teams coordinator Steve Hoffman, offensive line coach Frank Pollack and linebackers coach Johnny Holland following a 4-12 record in 2012.
"Decisions like this are very difficult," Raiders head coach Dennis Allen said in a press release. "I have a great deal of respect for all of these men and I appreciate their contributions to the Oakland Raiders this season."
The Raiders saw a big drop in their running game, going from seventh in the league in rushing in 2011 to 28th this season.
In addition, Oakland endured noticeable drop-offs in yards per game, points per game, rushing yards per game and rushing touchdowns.
This was Knapp's second stint as Oakland's offensive coordinator. He held the same job with the Raiders from 2007-08.
