How could the top hand be fairly passive? Each finger, hand, elbow has some value in the swing mechanics. For me the commitment to swing starts with the back elbow beginning to lower as the lead elbow begins to make a good first move forward and up like the elbow was going up a ramp. The knob of the bat is moving forward in my mind and I hope I can control the angle of the bat as my hands are moving forward. Take away the fairly passive top hand and what is lost? The hands and elbows, arms etc are trying to function as a single unit at the same time. Again look at the complex movement that is required and explain how it happens in your mind and then how to communicate it to our students. Just saying the bat head goes rearward is like explaining a bullet just came out of the barrel and there are consequences for both actions depending on where the BARREL is pointed if you get my meaning ie hollow points, blue tip, jacketed. The size of the bat and your ability to communicate to your student what it should look like and feel like is your ability to teach hand path and hitting. It is easy to see and the art comes from the ability to teach it. Forearm strength is the last on our list of must haves, flowing to the ball, weight shift and hand path are key facets to the hitters seeing what we teach and feeling what we teach and fixing it and that comes from being a teacher and Crystl Bustos does that very well at her clinics and individual instructions. If you could talk hitting with Bonds for $90 an hour would you do it? If you could talk hitting with Bustos for $90 dollars an hour why would you not do it, especially if she could make it measurable and observable and show you how to test for it? Most who could take the opportunity do not and maybe they fear learning from a female is too humbling of an experience...there loss!