Assuming we come up against a 3-4 offense, the defense sets up as illustrated. The mark is fronting; this isn't a "force middle". Defenders 5, 6 and 7 are all marking their defenders under, i.e forcing them long. As it is easier to flick-huck than off the backhand; 1) Defender '4' covers deep, as they can see most of the field. and 2) The other defenders marking the cutters cut off the flick-side more so than the backhand side. The dump-marks are forcing their opponents backwards for the dump; there is too much space here to allow them up the line.
If the disc is dumped to the "break-side" (not really the break-side, but it's easier just to call it that), 4 and 7 swap roles guarding the deep. 7 can come across more; very risky throw to his man.
If the disc gets swung over to the "open-side", 4 reverts back to being the deep.
Profit!