In general terms, could it be an evolution of the swing instruction from one generation to the next? The older player using techniques from their generation, and the modern player using "newer" mechanics. The "level" shoulder being more of an upright or two plane 70s ideal vs. a more rotational swing around a more angled spine which moves the left shoulder down.

On another point, I’ve noticed several of the new young guns are back to a severe reverse C finish, which was all but abandoned in favor of an upright, facing the target finish, allegedly because the reverse C was causing back injuries in the long term.