I still think a complete re-design of the helmets is in order. The first thing to go would be the hard outer shell, which causes players to use it as a weapon and transmits too much of the impact. Replace it with a soft but durable outer coating with a foam layer underneath. Below that a thin, hard layer, possibly carbon fiber, to protect against crushing damage / skull fractures. Inside that a thin rubbery gel layer and finally form insets for fit and final shock absorption. Attach the face mask to the hard middle layer with stiff springs. The whole thing would be made to reduce shock transmission to the brain but cold still be a similar size and weigh to regular helmets. It would be more like how a car protects squishy humans by having crumple zones on the outside, a stiff protection zone and some shock absorbers (air bags) on the inside.