I was kinda of reluctant to change my way of pitching. But after lots of control issues and lot of pain on my shoulder I was convinced to change. And I think it was the best thing I could ever done.
I have read on many books and articles on the internet that a coach should never change the way someone pitch. I think if the guy can pitch well and doesn't hurt himself, I think they might let him pitch that way, but that was not my case and that's probably not the case of most beginners.
Dontrelle Willis has one of the most weird deliveries I have ever seen, but he can maintain himself healthy and throw consistent strikes.
So I'm with you Chris. I think it's not a genetic thing. I think it's more like a preference thing. Maybe the kid saw someone on the Majors pitch that way and start pitching like that.
I don't think every coach should try to make their pitchers become a overhand pitcher also. It worked for me but it might not work for one of my teammates.