When disc is in the center, red 2 puts on a straight up mark. Red 1 and 3 sag into the lanes to help with any downfield throws. Downfield defenders sit on back shoulder and take away deep threats.
When disc moves to blue 3, red 3 snaps and flashes the mark on the shown throw. Red 2 moves toward helping in the lane. Red 1 moves toward helping with blue 2.
After flashing the shown throw, red 3 forces sideline. Red 2 sags in lane to help cover under attacks from blue 5 and 6 and an up the line cut from blue 2. Blue 1 shifts over to help cover swing pass to blue 2 or 1.