He clearly doesn't know how to handle his emotions very well, and I don't just mean what happened yesterday. He has quite a track record of bizarre behavior, but without knowing him personally its really just a guess at what the cause is, there could literally be an almost infinite number of reasons - such as having a poor upbringing which leads to immature or egotistical behavior, or perhaps an undiagnosed mental issue (possibly from chronic head injuries since he plays in a high speed contact game)... but from our distance we just have no idea. I would only say I pray for him to realize the error of his ways and if he needs help, that he finds it... part of the problem is that he was blessed by God with such physical ability, that NFL teams are more than willing to "look the other way" which only means he never gets whatever help he needs, and he is actually encourged to never perform any self-introspection... it is part of the problem of our modern world in my opinion, and most especially in sports. It certainly was a bizarre scene and we still don't even know why he did it... we may never know, he might never be willing to divulge the reason and his teammates sure aren't talking about it.
Sometimes, "hitting bottom" is the only time we actually make any real progress, such as people who suffer with addictions like alcoholism know this concept very well. Perhaps the best thing that can happen to him is being shunned and thus, hitting his own rock bottom, as cruel as that may sound.
