James Young wrote:
the tenkan, or kaiten movement if you prefer, I think is used to put the uke in momentum that the nage controls (because he has connection with him) and then to put the uke in a kuzushi situation where he loses his balance at which point the nage can change direction (whether it be reversal like for irimi nage or towards the outside of that rotational sphere like kaiten nage) and then throw the uke with ease.
Yeah. That's what I was thinking. More in the instance of moving uke in a circular orbit. Closer to your body as you move them around, then wider as the momentum is built, whether you are letting go or reversing the direction of the orbit. I think the elliptical levers in a compound bow work the same way?