When the disc is in the middle third of the field, the Mark sets a straight up force. The two Lanes set up on either side of the disc with the goal of stopping easy yardage gain. Swings are left uncontested while the disc is in this position.
When the disc is swung to a sideline (either the left or right thirds of the field,) the Mark forces towards that sideline. The Lanes transition as seen here, with the Lane on the open side of the field blocking upline throws and the Lane on the break side faceguarding the center handler.
When the disc moves back to the center of the field the Mark and Lanes set up in their original configuration.
If the disc is swung to the opposite side of the field the Mark again forces sideline, with the Lanes switching who stops upline throws and who faceguards the center handler.
When the center handler makes a cut directly behind the disc, their defender will peel off and shut off the around.
A yardage loss without gaining field position is the ideal outcome in this situation.
Similarly, the Lane will follow strike cuts until the Mid Mid (more about that on the next play) picks up the cut.
They will again fall back to stop the swing.
If the disc does advance, the cup follows.
The open side handler will be left open. We want the disc as close to the sideline as possible
The same collapse occurs when the disc is swung the other side, but the lanes switch.
Communication is the most important part of this zone. Work together or bad stuff happens.