There is growing evidence that brain trauma sustained by NFL football players could lead to profound, long-term cognitive disability. But did the NFL turn a blind eye to the problem?

It's a troubling question but one that must be asked. And it would have been. ESPN and the PBS public affairs program "Frontline" were collaborating on a two-part report that was going to air in October.

Published reports say the NFL told ESPN officials they were displeased with the direction of the documentary so the network pulled out.

Greg Aiello, a spokesman for the NFL, said, "At no time did we formally or informally ask (ESPN) to divorce themselves from the project…We deny that we pressured them."

Facing litigation that could cost the league billions, the last thing the NFL wants made public is more evidence that its officials saw a dangerous trend and did nothing.

But the NFL represents a cash cow for ESPN, so it's not surprising the network dropped the project. No "pressure" was really required.

Anyone who has ever played organized football has had their "bell rung." Sustained ringing of that bell, say experts, can lead to dementia and worse. There is a long list of young and old NFL veterans incapacitated by head injuries.

But football is an assumed risk. You know it's a violent sport and your risk of injury is high. The equipment, including the helmet – and many advancements have been made on helmets since I played high school football – is no guarantee you won't be hurt.

So did the NFL disregard player safety or did it offer its rabid fans a high level of competition played by exceedingly talented athletes who understand the risks and are willing to assume them?