User blog comment:Master Sima Yi/Assassinews 05-08-'14 – Assassin's Creed: Rogue announced/@comment-4254431-20140905131951/@comment-13471981-20140905160748

The way I've heard it is that a mission Shay was a part of went wrong, possibly due to Shay's own actions. In response, the Assassins tried to kill him and he barely got away or something and was helped by the Templars to recover.

It sounds a bit awkward, but I guess we'll have to see when the game comes out :s