No question permanent brain damage has occured in longterm head slammers. Sadly, some men are more susceptible. Prolonged careers of head bangers like Junior Seau, Mike Webster are well documented.
However, if you send a brain to a brain lab that's soul purpose is diagnose/study CTE, I think they are more than likely going to find what they want to find. I hate any hollywood movie that pushes fear and one side of the story. (Big NFL Corp Bad bad, Football players victims victims, fear fear). What's suprising is the number of college athlete's that have forgone the NFL because of the fear that they might get a concussion, not that they have a history of concussions. It doesn't take a rocket scientist to see the fear is influencing the decision to participate or not at the lower levels.