Offense set up in a horizontal formation.
Defense sets up Shadow zone. RED 1 will not be part of the cup setup. Rather they will be shadowing the breakside handler, i.e BLUE 1. The rest of the zone sets up in a cup, 2 mids and a deep (compressed in field)
Disc is swung to BLUE 3. RED 1 proceeds to shadow breakside handler i.e, BLUE 2. Cup traps sideline and does not allow return passes. Meanwhile the rest of the upfield zone compresses to the side.
In an unfortunate scenario when the disc is swung to the extreme end BLUE1 or sometimes BLUE2, the cup will continue to trap sidelines and does not allow return passes. However right now, the new shadow is player 2. Shadow player have to communicate with "forcer" in the cup to setup an effective trap. Most likely shadow player will mark no dumps,