Coach Campbell or In The Trenches?

In the trenches is one of our line coaches and I'll help him out here. When ever running the stretch play which we call 44 and 45 Stretch into the 4-3 scheme with a 9 to a 3 tech. towards the tight end it is done like this. With the stretch play I teach a drop step tech for the offensive line pulling any backside uncovered lineman with you. So, to a 9 tech. with tackle uncovered the tight end would alert trey thus tight end and tackle tracking the 9 tech. to the sam linebacker. With the stretch play each linemen is trying to off the dropstep to stretch the defense and bring their backside arm and leg through the playside jersey number of the down defenders. lets take this further. Coach CAmpbell

Coach what do you mean by "pulling backside uncovered linemen with you"

thanks