McDermott's goal is not to make a magical zero deflection shaft. It is concentrating more on hit and sound. They use marketing gurus who tell McDermott that hit and sound are very important even if the design increases deflection more than others. Their advertising may, however, be less than clear on this.
As far as the bounce test, take a look at the Jewett/drdave video. Search, too, here for dead blow hammer.
One thing McDermott does is experiment. They don't do the same thing as everyone else. They are not on a race for low deflection. They have concentrated instead on a hit, sound, feel.