I can't speak to the severity that Frank Gifford suffered due to his CTE, but his family must have recognized something because his brain was tested after he died. CTE causes the brain to behave abnormally. The severity of the abnormalities vary, but severe cases have been difinitively diagnosed. It can represent as memory loss, depression, elevated aggression, and neuro-motor disfunction. The fact that sever cases of CTE cause not only a danger to the health of the person with CTE, but a danger to others as well, is why this is such a big issue.
Chris Benoit murdering his family as well as taking his own life, Jovan Barker killing his girlfriend before taking his own life at the Cheif's facility, Strzelczyk driving into oncoming traffic, these are the reasons why CTE is such a big deal. Causing athletes in their 30's 40's and 50's to be a danger to society and themselves.
It's why players are retiring under the age of 30 now. Worlids, Willis, and Locker retiring young, and Borland retiring after one year because they feared for their health if they continued playing football. This is NOT going to be the exception to the rule, this is the new norm. More education on head trauma will cause athletes to leave this sport in the next decade. The game will never be the same, and it's never going back to smashmouth. This game will be closer to flag football when all is said and done.