Awesome graphic! Seriously, I love me some MS Paint!
One way I've described this is that when you ground force into your back foot exclusively, you actually create a stable bridge between yourself and the pusher. If all you're concerned about is not being pushed, yay, you did it. But if you want to have any hope of turning these static drills into dynamic martial movement, it's a dead end.You have to be able to be able to ground (receive, root, direct...) that push force down through the front leg. Why? Well looking at Hunter's image, grounding through the front leg is under the incoming push, so it's disrupting the pusher's stability. When it comes through the back leg *exclusively* it is in opposition to the pusher's force. HOW to actually do that is probably outside the scope of a forum post. And all the usual disclaimers, this is glossing over a lot, overly simplistic, etc, etc, etc...
Bonus, more MSPAINT!
And it is yet another reason those one legged army
guys who keep trying to make four legged animals out of people with seriously connected bodies end up being so easy to handle.
1. It is too slow and is dependent on a connection to the other person
2. You feel it coming a mile away
THEY are relying on making a bridge with you...but there is a way to train your body that makes it damn difficult....DAMN difficult to bridge or connect to. Most often when THEY try it they are gone and they don't know why. You are under them before they started... and under is just one small piece of your available arsenal.
By the time my enemy arrives....my ki has arrived behind them......Ueshiba Morihei