Former NFL MVP Warner's Concussion Concerns

But not all of Warner's former colleagues agree. Amani Toomer, a former New York Giants receiver, responded by saying Warner's comments "trash the game" and that he should "keep his opinions to himself," pointing out Warner's current job as an analyst for the NFL Network. Asked about that criticism, Warner said he disagrees.

"The game has been incredibly good for me and my family," Warner said. "But at the same time I think as an analyst and as a person that's played that it's important and it's our responsibility to also share the concerns."

Warner said at this point, he's not planning to donate his brain to researchers who are looking at the impact of head injuries, and that it may be more appropriate for other players, such as linebackers, who are involved in more hits and collisions.

If the level of violence in the NFL is lowered, Warner said the game will still be attractive to fans. "Of course, I don't want it to see it become flag football," Warner said, "but I think if you came out and had these great athletes playing flag football, people would watch because these guys are so special and so rare and so talented, so unique in what they do that people will still tune in. So I think yeah, you can make changes to this game and it can still stay the number one sport in this country."