League of Denial: The NFL, Concussions and the Battle for Truth by Mark Fainaru-Wada and Steve Fainaru:
The NFL, in a refrain that would seem eerily familiar years later, downplayed the crisis. Greg Aiello, the league’s director of communication, repeatedly told reporters that the rate of concussions since 1989, when the NFL began to keep track, was unchanged: one concussion every three or four games. The data, Aiello said, had been collected by the teams and passed on to an epidemiologist who had crunched the numbers of the NFL’s competition committee. “In the big picture, when you consider the number of times the head is impacted [in pro football], the number of concussions is relatively small,” said Aiello. “But hey, they do occur. And maybe there’s more we can do.”
But of course it depended on how you counted concussions. The league, Aiello acknowledged, was counting head injuries as concussions only when a player lost consciousness or was seriously dazed. Garden-variety concussions were not part of the program. Joe Maroon did his own calculations and estimated that two to four concussions occurred in every NFL game.
That discrepancy perhaps should have raised red flags. At minimum, there was a 156 percent difference between the rate of concussions reported by the NFL and the rate reported by the senior neurological expert in the league. Maroon said that he, for one, was quite concerned. But few people seemed to notice.