We're still so early in learning more about CTE that it's hard to really draw any concrete conclusions from these studies in my opinion.
For example, these studies have revealed that even NFL kickers/punters and MLB players suffer from CTE; these guys are hardly ever taking trauma to the head. It seems to me that CTE may just be very easy to develop (ex: Ryan Freel, who was noted for being hit in the head with a baseball once and colliding in the outfield with a player once) suffered from CTE. If suffering just one or two hits to the head is enough to develop CTE, there is simply nothing that the NFL, NCAA, or high schools will ever be able to do to prevent it.
To be fair, those 111 former players were studied because they believed they were at risk of CTE, so it naturally skews the data towards a positive diagnosis.
I'm no neuroscientist (I was actually really interested in it and tried to take neuroscience courses at Syracuse, but I literally got a zero on my first multiple choice exam and dropped the class shortly thereafter), but I take this stuff very seriously. It seems like there's a lot of relatively easily fixable issues with the way these studies have been conducted.