Thanks 1Player... I do appreciate your feedback. To answer a couple of your questions..
His shot shape is currently a fade. He sometimes switches this up to get a scenario where he knows which way the ball if falling (left or right).
His miss is normally a hook left. Sometimes its a push. He has an inside out swing and but its between 1-3 degrees. His coach has him working on shallower swings with the driver so his angle of attack isnt so steep.
I personally think its more fundamental like tempo and the smoothness of the transition.
I guess my big question is
should we have expected significant improvement in ball striking after working with the same instructor for 2.5 years?
One think this instructor says frequently to us is that we tried to many instructors in the past. However he has only had 2 primary instructors the past 6-7 years althougth we have tried seeing others occassionally. (ie, 1 times with that pro, 2 times with that one, 1 time with that one over the time frame).