This article from AANS regarding traumatic brain injury (TBI) data from 2012 discusses sports related concussions and the more serious brain injuries and injuries to the cervical spine.
Defensive backs in American football are at the greatest risk for both fatal head injury and serous cervical spine injury. Quoting the report:
"The majority of catastrophic injuries occur while playing defensive
football. In 2012, two players were on defense and one was in a weight
lifting session. Since 1977, 228 players with permanent cervical cord
injuries were on the defensive side of the ball and 55 were on the
offensive side with 44 unknown. Defensive backs were involved with 34.6
percent of the permanent cervical cord injuries followed by member of
the kick-off team at 9.2 percent and linebackers at 9.5 percent."
Spending even a small amount of time watching high school,college and professional football on TV makes it clear that the vast majority of high impact collisions occur in the defensive zone involving defensive backs and either runners or receivers and on kickoffs.Quarterbacks receive many hits with the helmets impacting the ground and have a significant risk of concussion but apparently have lower risk of fatal injury or injury leading to permanent disability.Offensive linemen may receive more sub-concussive head blows over a game or a season and whatever the long term consequences of that may be but seem less likely to regularly be involved in high impact collisions and therefore less at risk for serious brain or cervical spine injury
Don't let your babies grow up to be defensive backs