I'm sure the helmet will help. This is physics. The potential and kinetic energy of a helmet or the ground (or whatever) hitting another helmet has to go somewhere. With conventional helmets, the energy is not transferred to the receiving helmet, due to its stiffness, and travels to the skull instead. These new helmets are designed to adsorb as much as that oncoming energy they can. They may even break in some cases, but this would be a good thing.
Evolutionary, the fluid around our brain does a similar thing. It absorbs the energy of trauma so the brain isn't hitting up the inside of the skull. Same thing with the fluid in our automobile shocks.
This isn't about eliminating brain injuries, but about decreasing their risk.