My "try it", in this case, was check swings and dry full swings in my office with a small bat. The focus was on trying to feel the "extensor action" being discussed. With the feel of "extensor action" (as I understand it) I also noticed the external rotation in my shoulder. If the external rotation is something that shouldn't be happening, then I will spend more time with it. If it is, then I guess I'm feeling what I'm supposed to.