Yes that occurred to me, the sample was flawed, plus with the law suites and stuff. But I shared that article when it came out few days ago with the guy who started next to me for four years (in the lowest division of football) the NAIA, because we both had some bad ones. He chuckled like it was only in the pros (He's a mess; Six back and two shoulder surgeries. He's been managing pain for years).
We played in a different era - 941 is right about the NFL, but that doesn't stop there; you never let someone get a chance of taking your spot because you're hurt or getting treatment. Back then OL couldn't use hands. From junior high on I was taught to lead with my head. I broke cage-style face masks in high school and college.
I guarantee it effected me. I got one early in a bowl game, knocked out for maybe 5 seconds or so I was told. I played the whole game. Finals were a month later, and I had a bitch of a time studying. Tough concentrating half of the next semester too. That was my soph. season, I got another my Senior year. Gary, the OG next to me had at least 6-8 of them in four years. He hardly left the field either.
We were a long way from the NFL, but at least one of our teammates committed suicide (25years after), and one of our FBs we know is dead but never heard how - he had a few. My high school teammates at another NAIA school (Bethel College, where my son went) also had a teammate commit suicide 25 years or so afterwards.
Nobody looks at it all the way back to high school. BUt that may be intentional - I bet it would be pretty scary numbers.