Rex Ryan is the head coach of the New York Jets. Rob Ryan is the defensive coordinator of the Cleveland Browns. Buddy Ryan's third son?

He's the head coach of the San Francisco 49ers, the team the Eagles will play today at Lincoln Financial Field.

Mike Singletary, of course, isn't really Ryan's son, but his football philosophy was definitely molded by Ryan. The two men spent five seasons together in Chicago, with Singletary as the all-pro middle linebacker and Ryan as the mastermind of the 46 defense that led the Bears to their Super Bowl victory.

"There is a lot of Buddy in me, unfortunately," Singletary said. "You can't get away from it. He's a guy who had a tremendous amount of influence on me, and a lot of the way I deal with players, discipline and those kinds of things, definitely come from a Buddy style of system."