For the second time in two weeks, the Rams have added a veteran cornerback to compete for playing time in their nickel and dime coverage packages, reaching a one-year accord with unrestricted free agent Lenny Walls. The five-year veteran, who played for the Chiefs in 2006, is a big, physical cornerback (6-foot-4, 195 pounds) with potential, but a player whose career has been slowed by injuries.