Many dogs are excellent protection dogs when the are allowed to bite and then win the sleeve. Watching a dog learn to subvert their personal wishes to those of their owners is both a fascinating process and a significant learning opportunity. Many dogs that appear to have excellent aptitude for working wash out when they have to subvert their natural drives at one moment, and reawaken those same drives seconds later. Throw the tennis ball a few times and allow a natural retrieve. The next time, throw the ball and call the dog back when he is half way to the ball.
Next time throw the ball and let the dog retrieve.
Alternate these activities, randomly throwing with or without a call-off. That might give you some idea of the challenge of training French Ring dog for the call off on the face attack. The dog is called off within 2 meters of the decoy, more than 50 yards from the trainer. In the ideal performance, the dog returns to the handler's side as intensely as he runs to the attack. The information, however, is invaluable to a breeder who is seriously interested in taking all aspects of their Belgians into consideration in their breeding programs.