Robert M Watson Jr
I can't really tell ... Seem like somehow the 'attacker' either has good structure or structure is established by the 'pusher' (in the attacker) otherwise there is nothing for the power to "go into". Kind of like one cannot push with a rope very well since there is no structure to convey the force.
Exactly. But to truly attack you, doesn't an attacker have to commit forces into you? What is jin/kokyu but the ability to manipulate the forces that an attacker puts to you, in combination with the forces that you yourself are able to generate? I.e, once you know how to do it, it's a statics analysis. Go back and look at all the "ki" demonstrations as statics analyses and they're fairly obvious as such.
If Uke is, as you mentioned, "like a rope" then no forces can resolve in a hard statics analysis because Uke is not a committed part of the structural whole. I.e., when you see Uke's flying away from Tori's movement, they have obviously allowed themselves to be a committed part of a whole structure.