It’s not a contradiction. It shows that you can sustain head injuries without concussion symptoms. That’s what makes the Chris Henry autopsy so scary. He never missed a game due to head injury but he CLEARLY sustained head injuries. CTEs don’t occur spontaneously, so there’s only two possible reasons Henry had them: injuries sustained before getting to college, which is really scary because that means he had permanent brain damage from peewee or high school football; or it was from injuries in college and pro ball that were to slight to be noticed (aka sub-concussions). There’s no way to view the Henry autopsy without fear. He either had his brain permanently damaged as a kid or as an adult in plays that didn’t appear to cause injury, either way you have to look at the current crop of players as walking wounded, we don’t know what percentage of this year’s crop of rookies already have permanent brain damage from football, but it’s looking like the number isn’t zero.