This explanation of MIPS goes pretty much all-in on it being about rotation: https://www.torpedo7.co.nz/community/help-and-advice/bike/ge...
Edit if you prefer it directly from the marketing horse’s mouth: https://mipsprotection.com/
Edit if you prefer it directly from the marketing horse’s mouth: https://mipsprotection.com/
When you have suffered a concussion or an even more serious damage to the brain, rotational motion to the brain is the most likely cause.