decoy is afraid . and so he should be . the person holding the dog is supposed to be anchored , stay in one spot , with leash being the same distance at all time. The decoy then knows the zone in which he can move in and out of the dogs range (safety) , tension and frustration for the dog.
In this clip the handler is dancing all over the place, running toward the not-a-decoy man , leash is slipping feet - growing (flexi lead idea) . The decoy is not offering an opposition or power . All bites front tooth snags so bad bite habits .