I just read that myself, but after 20+ years it is no surprise to me. I had a feeling Transatlantic and his other side projects would leave him hungering for more challenges outside of DT. I read he is asking his fans to Not blame Avenged Sevenfold for this, he doesn't have to worry about me I don't like AX-7 at all.
But I wish him well, he has handled this whole matter with class and everyone understands when you lose your passion for something to continue doesn't make sense, I would feel the same and out of respect for his band mates he has left them plenty of time to get a replacement for the new album and world wide tour next year.