"Vertical Ground Forces" are a big part of the golf swing, and are taught in many different ways. Homer Kelley once said that he expected the golf swing to continue evolving for all time. That doesn't necessarily mean he expected us to redefine the structure of his work.
IMHO, the Power Package and it's Accumulators and Pressure Points are very well defined, and understood by anyone who studies the work. I don't think the definitions need to be messed with.
On the other hand, what a great add on for instructors who understand it!
I never understood what I was supposed to feel through the ground, and how powerful it could be until YODA showed me the basic MacDonald drills, specifically the one dealing with Left-Right-Left-Right. What an eye opener! There were times of course over my career that I had the "feeling", but until YODA I didn't understand why.
My opinion may not be popular in this new high tech world of teaching, but I want to learn the Machine as Homer Kelley intended, then go from there and form my own opinions. Believe me, I read and try to understand EVERYTHING I can, and I always come back to this basic structure.
Kevin
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I could be wrong. I have been before, and will be again.