Initial setup
Disc swings, but not to sideline. Focus is on stopping upfield throws. Middle mark is flat still, note the markers showing where the side mark goes on.
Back and forth in the middle of the field means a lot of running for the middle mark. We only care about upfield passes. Side marks can tighten in and help if there is no threat on the sideline.
Side mark needs to stop the next throw up the sideline, just like capping a break throw.
If the middle mark gets pulled too deep, it opens a lane to the far side handler. Not ideal but we can recover.
The disc is right on the edge of side mark vs middle mark territory, just remember the priority is to stop the next pass, to give us time to reset. Note that the deeps have helped cover the next option.
It's a bit of a scramble to get back in front of the disc, just like any zone. Focus on taking away the next upfield threat, wherever that is.
Here we've basically reset. GREAT SUCCESS!