When the Hip Shifts, the Spine -- the Axis for the Shoulder Turn -- Tilts (lower portion toward the Target / upper portion fixed by the Stationary Head). This enables the Right Shoulder to thrust and support the Handsdirectly toward the Ball. Now . . .
The Hands, in full command of the Hands-Controlled Pivot, can aim their Straight Line Thrust toward the Ball.
Drill: From the Top of the Backstroke, throw a golf ball at a golf ball on the ground. Clear the Right Hip, then . . . Straight Line Thrust. No matter the Path of the Hands -- Straight Line or Circle -- that's the idea.
That is one of your best! As simple yet complete a description of the transition and downstroke as you will ever find!
Thanks , Yoda- not tiring despite 7000 + posts!