Y'know, another angle on this whole thing springs to mind. Given his (apparently sudden) propensity for violence, it would be interesting to look into his history of concussions and getting his bell rung.

I bring this up just remembering the case of Chris Benoit, the professional wrestler that murdered his family and then killed himself a few years back. He had endured so many concussions over the years that his brain was severely damaged.

Now, granted, Aaron Hernandez is considerably younger than Benoit was, and has likely absorbed less punishment, but it is still something to consider...it doesn't excuse what he did, but it is another possible explanation.