Initial setup (disc centered): (2) is the "center" and sets a flat mark, while (3), the "monster" roams behind, shading slightly to the thrower's backhand side (because a flat mark shades slightly flick). (1) and (4) are "shallow wings" pressuring the handler space, allowing flat swings, but preventing upfield yardage gainers.
(5) and (6) are "middle wings". In conjunction with the monster (3), they will prevent the poppers from getting anything easy. (7) is your traditional "deep-deep". The recommendation, in mixed, would be to put your female-matching players at (1), (2), and (4).
The monster (3) takes the first popper to enter the space in front of the handlers.
...and backs out if that cutter clears.
If both poppers go simultaneously to split the monster, the forehand-side middle wing will follow in. The backhand-side middle wing will back up and cover a potential hammer, and the deep deep will shift and cover the other offensive wing.
This scheme is the "box". Let's look at what happens on a swing.
On a swing to the sideline, the shallow wing becomes the mark (4), forcing middle, the monster (3) acts as the middle of the cup, and the center (2) plays the far side of the cup. The closer middle wing (6) shifts to take away anything over the top to the closer popper, and the deep-deep (7) shifts over and takes away deep shots down the sideline.
The far-side shallow wing can now pinch to the middle and challenge the swing back to the middle.
The far-side middle wing (5) looks for anything over the top, including to the far offensive wing (Blue 6). At your discretion, you can also try to challenge a long swing back to the other side (1).
...like so.