MIDFIELD—As their opponent prepares to snap the ball, ranking members of the defense, which is currently positioned for a blitz, are cautioning their members to be alert for the possibility of a blitz-evading screen pass. "Watch the screen! Watch out for the screen!" said one top defensive player, whose position in the very middle of the formation is generally considered to give him a better view and thus a better opportunity to predict the actions of the offense. "Screen!" Meanwhile, sources in the defensive backfield, while not ruling out the screen, are said to be considering the possibility of the offense running the draw.