Great work as always, Matt.
Another thing I noticed (you might have said it differently) is the position of the top hand. In the pictures on the right, the top hand appears to be behind the bat better. That helps with staying on plane as you mentioned.
I think it is something as subtle as "lining up the knocking knuckles" on the hands. That most likely helps within handling the high cheese, too.
That, coupled with the long arm issue you identified, is making him a very good hitter.