[BerntR]

I think you have a point here. Straightening the right knee does something very similar to the pivot as straightening the right elbow does to the primary & secondary lever assembly. And straightening the left knee does some of the same. Depending on knee action of course.

But the feet are in this regard pure power generators as there is no power generated below the knees to accumulate and release later. They do not release stored energy. They just work the pivot and the levers.

The power accumulators release stored energy. They transmit accumulated energy from the moving pivot and delivers it to the ball. And some of this energy was produced by the knees stretching.

While the power accumulators don't really accumulate power, they are the enablers of accumulated energy being transformed to force & speed through the ball. And to some extent they are power sources themselves.

There's plenty of mentioning of the role of the pivot and the feet in the book. The power generat from the large bodyparts aren't neglected at all.