Dorothy DeLay question.?

I'm sure not (or she would have had a significant career doing that as well). But that does not take away from the fact that she obviously had great teaching chops. Honestly, I would say that my experience is that very few great players are also great teachers because often things came very naturally to them so it is hard for them to explain to normal humans what they need to do to overcome problems. Often the best teachers became that way because playing was not natural for them and they had to figure it out.