An NFL statistic that would be interesting: Concussion count (player/team/records/etc.)
I’m sure the data are available, and it would be interesting to see such things as whether a team’s win rate and concussion count are positively correlated. Or not. And which team leads each league in concussion counts. All-time record number of concussions—player, team (all seasons), team (one season), by salary level, and so on.