That 's when the quarterback drops back to pass .
One of the linemen -- who is ineligible to receive the ball -- runs past the line of scrimmage without blocking an opposing player ( as offensive linemen are supposed to be doing ) .
That 's when the quarterback drops back to pass , and one of the linemen -- who is ineligible to receive the ball -- runs past the line of scrimmage without blocking an opposing player ( as offensive linemen are supposed to be doing ) .