So what you are saying, is that past performance does not accurately predict future results and each case should be reviewed independently.
I actually disagree with your comment though. There's no way to prove it, but I strongly feel that there are a LOT more players out there in contact sports (football, hockey) that have had multiple concussions than we will ever know about, and went on to have fine careers. It's only recently that it's gotten the focus it has and the procedures are in place to identify even minor ones and take action. The extreme cases (career ending or god forbid, the long term effects result in much worse) are the ones that get the most press. In the past, guys got "their bell rung" and missed a game or two.
And it wasn't that long ago. Aaron Ward in the 06 Cup run admitted he can barely remember playing in 1 game but refused to come out because he knew he wouldn't pass a baseline test. Troy Aikman claims he suffered 7-8 concussions in his career and one time, suffered a concussion so severe in the 1994 NFC Championship Game that he had to be hospitalized, and then played in the Super Bowl anyway. It was his back that eventually led to his retirement and he's had testing and insists he has no long term ill effects.
There are plenty of examples of that, way more than guys careers ending IMO.
Again, I'm not saying "don't worry" because any time a guy his age has 3 concussions, it's a concern and the long term implications of repeated concussions are not fully known (some guys have impacts, where-as guys like Aikman have no impacts). Just that we also shouldn't over-react either.