Ok, first of all I think we are getting FAR TOO ANALYTICAL about all of this. Extremely difficult to debate w/ words alone. But it is kinda fun at times.
So now we are discussing (again) if the back leg is used to help drive or fire the back side to the ball or if the middle (core) of the body pulls the back side to the ball.
I will admit what I'm about to say is very analytical in itself.
Big league hitter, hitting on a sheet of ice (let's say a hockey rink). On his front foot he wears a shoe that would completely prevent slipping. On his back foot he wears nothing (bare foot).
If the middle pulls the back side to the ball then the hitter should theoretically have no problem swinging the bat (maintaining balance etc...).
Let's also assume that the hitter uses no stride. I think what you would see is the hitter greatly struggling to even perform the task of swinging the bat w/ any force at all.
I think you do indeed use your back leg (and front) to fire the back side to the ball.
I 100% feel the legs are extremely important and they actually greatly aid in the fireing of the back side more so than anything else.
I also do not want to debate this. So basically I agree to disagree w/ the thought that the middle pulls the back side.