He also performed well against Michigan, recording five tackles, two sacks and a forced fumble as the Hawkeyes lost to the number two team in the nation. Named honorable mention all-Big Ten by both the media and the coaches, his four forced fumbles were fourth in the Big Ten and his seven sacks ranked eighth in the Big Ten. Mattison was shifted from defensive end to guard in 2009 with the Baltimore Ravens. He spent parts of four seasons with Baltimore, before being waived on November 24, 2011. On November 25, 2011, he was signed by the St. Louis Rams. On September 26, 2012, he was signed by the Kansas City Chiefs. On May 2, 2013 Mattison was released by the Chiefs. Mattison decided to retire from professional football in the spring of 2013, and turned down an opportunity to tryout for the Carolina Panthers. He spent the 2013 fall season serving as a volunteer assistant football coach at Penn High School, his alma mater in his hometown of Mishawaka.