During the 'around' the upper rear arm is lowered by two engines ... the torso engine adducts the upper lead arm, and supination of the rear forearm adds to the slotting/lowering of the upper rear arm. You don't force the upper rear arm to lower via the shoulder ... it's more a combination of the torso engine and rear forearm. Get this right and the feel of a double pendulum can be felt.
For many young developing hitters there isn't even a mentality to pivot the barrel. The 'around' is absent ... they rush to perform an 'along'.
Getting them to pivot the barrel requires the learning of new mechanics and the changing of a hitter's mentality.