Yowzer, gotta agree with Fab on this one. The reason Seau killed himself is on him, not anyone else. No one made Junior play ball, he played it because at one time he loved it.
If Biggs is the reason then we all are the reason. Players get hurt, sometimes tragically altering their lives. Daryl Stingley was paralyzed in a football game, and while that affected me at the moment, I still played and I still to this day watch the game. Guess what, if there is no demand for college or pro football, then no one gets injured. We have football because we want it and supply meets demand.
What is a bigger take away is this....Tyler Hillinski may be a very key study that tells us if it is a series of hits, or if one hit like the one he took at Arizona was the defining hit. If they discover that one hit can turn a happy go lucky kid to one that committed suicide then the game will for ever be altered.
From all that I have read his "depression" was undetected, no one knew, or it has been said no one knew.