i don't see a problem with this at all. you should use whatever your dog find rewarding while you are training. my dog likes his squeaky kong ball enough, but he is a total food monger so if i want him to pay attention i use food as his motivation. the only time i use the ball is when we are playing fetch. i throw the ball, he brings it back and he has to sit and use his manners before i throw it again. in that situation the ball is the reward...all dogs are different, so if the ball works for u, why not use it?