overturn is a signal for inefficient energy transfer. energy is transfered by stopping the earlier body parts in the kinetic chain.
that means the shoulders stop when the chest faces the net which causes the arm to whip through. the top players don't rotate with their shot but rotate early and delay their very fast arm strike till the very end.
Turn-Stop-Whip (but in one fluid motion which is the hard part
watch how early he rotates and how quiet his shoulders are at release