There are a lot of rules changes that can be made and most of them much more effective that what PR Goodell has implemented. He has instituted rules that make it less likely for replay to show spectacular hits. There is no evidence these are the problem.

Repeated sub-concussive hits to the head are still suspected as the culprit for a lot of trauma and the LOS is the spot those most often happen. So you back defenders and O lineman off the ball to create a yard of space. Gives players time and angles to get head out of the way. Enforce it inside the box. Wide 9 DEs are already OK.

Outlaw tackles with the head. No more spearing, Kenny Easley/Atwater hear seeking missile tackles can go away. Bring some technique back. No more attempting to force a fumble with the helmet. Emphasize rugby style tackles like the Seattle secondary makes (other than Chancellor).

When helmets were worse, there were more immediate head injuries (lacerations and fractures). But there was less using your head like a hammer.