Browns starting middle linebacker Anthony Walker Jr. was placed on injured reserve Friday after undergoing knee surgery, knocking him out of the playoffs and likely ending his season unless Cleveland makes it to the Super Bowl. One of the team's captains and most respected players, Walker hurt his knee in practice last month and had arthroscopic surgery on Dec 21. The 28-year-old Walker, who also calls signals for the NFL's top-ranked defense, made 12 starts.