yes...Supination is after/at launch
Understood .... But back to the "strong wrist".
You advocate a "strong wrist" beginning at "swing launch" .... how far into the swing do you advocate the top hand wrist remaining strong? By 'strong', what do you mean ... do you mean that the top hand wrist is stiff and in alignment with the rear forearm?
I do not teach to swing down on the ball...Down as in chopping down
What I mean by strong wrist is do not let the wrist supinate...lay the bat down
Strong top hand until the body reactively releases the barrel