Casting is part of a good approach. You have to cast a little to hit the outer part of the plate. The hands finish at different distances away from the body when looking at different pitch location. The hands finish differently between an outside pitch and an inside pitch. I have always called it mini casting. It's not a full on casting action, although there is some casting.
For those that are bit more hand-centric/barrel-centric ... it isn't the hands the are worked down, but the barrel ..... hands stay up, bat head is worked/released down.