"Keenan is an outstanding addition to our coaching staff," Shanahan said in a statement released by the team. "He has all the attributes that you look for in one to become an outstanding coach in the National Football League. Keenan has instant credibility with our players as someone who played in this league for 17 years, won two Super Bowls and played in multiple Pro Bowls. He will be able to pass along much of the knowledge and expertise he picked up throughout a great career."
This is McCardell's first full-time coaching job in the NFL. He completed a Bill Walsh Minority Coaching Fellowship with the New York Giants during training camp in 2009 and last month coached receivers in the East-West Shrine Game.
The Associated Press contributed to this report.