Why do the Dallas Cowboys' offensive linemen bob up and down when the team is running out the clock?

Answer 1

It's called the Landry Shift, and it's a tribute to Tom Landry, the Cowboys' original head coach from 1960 to 1988. Landry believed in a multiple offense, and he had offensive linemen bob up and down to disguise the movements of running backs and receivers before the ball was snapped. The shift was discontinued when jimmy Johnson became Dallas' head coach in 1989. The 2014 Cowboys only use the shift when they're in a victory formation in the final moments of a game.