I was wondering about that whole thing myself when I saw him slide and somersaulting before taking possession of the ball. I find the flirt pole scary and injury prone so I am not using it any longer. It looks more doable for terrier types to me.
The way I solve this issue is to have him on a sit or down stay, throw the ball and give him the OK to fetch it once the ball is not moving any longer. WD is less intense that way; I think because he knows where the ball is. It looks way better controlled , at least with him.
Another way: sit or down stay, throw the ball or hide it yourself, distract him with another command so he loses sight of the ball/toy and let him search for it.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015