Curtis Martin recently told ESPN.com, "I became an expert at covering it up."
During three seasons with the New England Patriots and eight with the New York Jets, Martin said he suffered "a lot" of concussions, including a brutal hit from Denver Broncos linebacker Bill Romanowski in the 1998 AFC Championship Game that knocked him out.
Martin's teammates knew enough to lift him to his feet when he was left dazed, he said. It's another rough narrative from the field, and we know current players are engaged in similar actions.
The NFL is hyper-focused on the issue, but rule changes alone can't alter the violent nature of the sport. Like Martin, today's athletes have found a way to live with it.