Each stack defender starts beside their cutter, then takes a half step downfield on the forehand side, where they can see both cutter and disc.
O7 drives deep from the back of the stack. D7 is already a step downfield, so they turn and run with O7, staying between O7 and the end zone.
O7 stops and cuts back under toward the disc on the forehand side. D7 follows a step behind on the downfield side and lets the short pass go.
O1 throws the under to O7. D7 has stayed close enough to set the mark as O7 catches, on the same forehand force.
The offence gained a few yards, but the long throw was never open and D7 is counting before O7 can look deep.