Once the offense has broken through the zone, the defense goes into a wall end-zone play. In the play, there are 4 wall defenders preventing an easy pass into the end-zone. Then there are 2 players back to prevent hammers and throws through and around the wall. Then there is the chaser whose responsibility is to force the disc to the middle to prevent throws around the wall.
When the disc is in the middle, the chaser plays straight up to maximize the chasers use. The wall compensates for the swing by moving to close gaps in the wall.
It is crucial that the chaser forces middle to prevent throws around the wall.
If the handler makes a large swing, the defender in the wall closest takes the chasers spot.
The defense keeps this up until the offense makes a mistake.