Flanking a dog has its purpose depending on the dog and your goals. It needs to be done by someone who knows what they are doing and such a person should be willing to admit they messed up some dogs before they learned how to do this correctly and it took a long time to learn how to do it correctly. Basically, the agitator is doing something similar to a stake out test but it actually becomes training rather than just a test. The dog is tied to a very short tie out. The handler leaves the dog and goes out of sight (but should be able to see the process so he knows what is going on with his dog and the agitator. After about 15 minutes, the agitator who is in hiding about 40 ' from the dog, slowly and suspiciously makes his way toward the dog. It is ideal if there is a line of something like Pine trees that the agitator can creep around in as he approaches the dog. What you want to see is the dog sitting or standing, holding his ground and not showing any avoidance behaviors such as turning away, licking his lips, sniffing the ground, lying down, etc. It is also ideal if you don't see a lot of reactivity while the agitator is a distance away and just beginning to suspiciously approach the dog. He will go very slowly, pausing at times, slowly pushing some pine limbs back and forth and not being in full sight of the dog. It is good to have an additional structure about 20' in front of the dog for the agitator to hind behind better. When he gets about 20' from the dog he will show some slow hand movements and be crouched down and at about that point, the ideal response is for the dog to bow up and/or hit the end of the short tie out and bark aggressively. If you see anything less confident than this, the dog has failed and the training probably shouldn't be continued. Each session afterward is a gradual progression of increasing stress which will eventually graduate to using the whip up close, hitting the dog with the whip, and if possible, flanking. For this to be of value, the dog has to genetically have some aggression that just needs to be brought out more. If as the pressure increases, the dog increasingly shows avoidance, he is washed out of this type of training. If the dog increasingly shows confidence, he will eventually learn that a person can hurt him and by aggressively fighting back, he makes the pressure go away. With the right dog, this will change the character of the dog, making him more confident, more readily aggressive and more suspicious of people, so that you will have to manage the dog in a different, more responsible way. The dog should have some maturity and a solid obedience foundation.