I think it has a lot more to do with the environment that most of the people who end up in the NFL are coming from, socioeconomically. They grew up with problems, they grew up around lots of people who had problems, they learned the patterns of anger-management, dispute-resolution, typical behavior in intimate relationships, the bounds of normal behavior, from everyone around them, long before they had a fancy public-facing job and a big paycheck to match. I don't think playing football had, or has, any meaningful effect. It might down the road, of course, from CTE etc. But mid-career? I think this is just an artifact of socialization.