Ball starts with GK and finds DM to knock ball around. Defensive line has to move/adjust according to where the ball is going, while maintaining shape. They also have to recognize an open ball or closed ball situation. The attacking team can decide when to drop the ball back to the DM or GK to initiate the "trigger" or open ball that will get played over the top of the back line. As that ball is played over, defends need to drop immediately while maintaining their shape to not get beat over the top. The two OF have slight head start and can go as soon as ball is played over the top.