I can't keep up with this thread. I am sorry for bringing back an older post. I agree with a lot of what you suggest. I found myself reading one of your longer posts at the beginning of thread thinking, yes, yes, yes, yes, no. I am having a hard time getting past "actively using the hand & wrists" to get on plane.Donaldson is the poster child for TTB.
I see the barrel path go backwards and getting on plane very early. Hands still very deep. My issue is exactly how to get into that "on plane' position. I am trying these things myself. I am finding, for me (an old out of shape dad who hasn't seen a gym is a long time), when I actively use my hands & wrists, there is definitely barrel dump. Or very specifically, what Donaldson is talking about here. "Too handsy":
Perhaps I am too over baking the use of hands & wrists.
In watching this gif below, I am seeing the TTB action due actively slotting the elbow. The hands & wrists are keeping the bat to forearm angle consistent, which turns the barrel as the forearm moves with the elbow.
As I said, so much of what you said makes sense to me. It is just this one part of the process where I am having a hard time reconciling. Am I misunderstanding something?