In the FWIW department, it was my experience that pitching instructors understood pitching mechanics, and at a high level understand workouts but none, at least the ones I met, were ever close to what you could get from someone like P3, Cressey, etc. Wolforth and driveline are kind of unique since they are baseball oriented and specific.
All you have to do is to go and poke around and see what they are doing and you can understand that a pitching coach would never have this knowledge base.