When the disc is in the middle of the field, the wall needs to stop the under cuts, prioritizing the cutter to their force side. The offense has various combinations of under cuts. Let's first take a look at the initiation cuts.
If the 3 primary force side cutters were to flood the under, the defense would respond accordingly. The mark has the usual responsibility of cutting off that I/0 break.
If one of those 3 primary force side cutters goes deep, the wall needs to shift to the break side one person, starting with the defender whose cutter went deep. That defender is responsible for initiating the "shift" call.
If the outside cutter on the force side breaks deep, then the entire wall shifts over 1.
If the middle force side cutter breaks deep...
Just the middle and break wall shift.
If the middle break side cutter breaks deep...
Only the break side wall needs to shift, so no shift call is needed.
Note: In all situations it is important for that force wall to be prepared to help with the under cuts, trusting their deep over the top. Now we are ready to discuss those combo cuts created by the offense clearing underneath.
As the middle two cutters come in, their assigned defenders cut them off accordingly. The force wall comes in to help, in the event the follow cut requires a switch.
If they both clear to the outside, a switch is initiated on the force side, with the mid wall sitting in the primary throwing line and the force wall picks up the force side cutter, while the break wall (D3) needs to be careful not to over pursue the clear, in preparation for the follow up break wing (O4) cut.
If the wings fills under, then the wall switches accordingly. and no additional help is needed.
So what if they both cleared break side instead?
The mid wall needs to initiate a switch, which the break wall should be expecting as they know not to over pursue the clear. The mid wall sits in the primary throwing lane, anticipating the next cut to come from O4 or O7..
No additional switch is needing to pick up the next set of under cuts.
Lastly, what happens if they both clear force side?
It is especially important that both defenders do not chase their clear cuts. This is because it opens up a wide throwing lane on the break side.
This throw look will be close to impossible to stop.
Instead, if both handlers clear to the force side...
the force wall initiates a shift, allowing the mid wall to switch to the training under, and the break wall to sit in the primary throwing lane.
So let's review.
Its important for the wall to move as a unit and be prepared to switch any time cuts clear to the outside.
Do not over pursue the clear. Initiate a switch to allow the mid-wall to camp the primary throwing lane.