Hi Carl, in my limited experience, when training with competent seniors in this style, no one has to "show you your role". They are able to control and move and guide you through the waza appropriately.
I think one of the main issues with these kinds of styles is can the run of the mill student in class or in a seminar do the same. I think the answer is...sometimes, sometimes not. And so the instruction for uke to maintain the connection to give nage a chance to practice and learn.
This can make this particular style of training very difficult...being honest with your self and your partner is crucial. Sometimes, I ask my partner in these scenarios to purposefully stand strong, especially when my results surprise me. Sometimes I find that I am doing the waza, sometimes I find ... uh ... not so much.