Roger Goodell wrote a letter announcing a $100 million funding to player safety and outlining a new initiative called "Play Safe, Play Smart" on the program's website.

Goodell wrote that the goal of the initiative is "to drive progress in the prevention, diagnosis and treatment of head injuries, enhance medical protocols and further improve the way the game is taught and played by all who love it."

Goodell acknowledged the NFL "can and will do better" in this area and acknowledged that some might think the league's motives are not pure.

"We know there is skepticism about our work in this area," he wrote. "That's why both the process and the results of our work will be shared with the medical community and the public at large."

The program will have "four pillars," according to the website: protecting players, advanced technology, medical research and sharing progress.