San Francisco 49ers center Marcus Martin (66) walks off the field during the second half of an NFL football game against the Cincinnati Bengals in Santa Clara, Calif., Sunday, Dec. 20, 2015.
San Francisco 49ers center Marcus Martin (66) walks off the field during the second half of an NFL football game against the Cincinnati Bengals in Santa Clara, Calif., Sunday, Dec. 20, 2015. Tony Avelar AP
San Francisco 49ers center Marcus Martin (66) walks off the field during the second half of an NFL football game against the Cincinnati Bengals in Santa Clara, Calif., Sunday, Dec. 20, 2015. Tony Avelar AP