h/t to Leaders and Best who mentioned it in a thread below.
I did a little digging on twitter and found this article saying that Aaron Lynch was absent from an Irish practice after leaving campus to go back to Ohio for "personal reasons".
Apparently he was involved in a brawl in practice, and subsequently "excused" from that practice. It's unclear whether that brawl was a factor in his departure.
Big BIG loss for the Irish if this goes anywhere...he led them in sacks last season as a true frosh.