Well that is very sad to hear about Dennis but I don't think that is the reason that he left. I'm pretty sure he was shown the door. On the day he left he called an emergency staff meeting and basically told them to watch their backs (I heard this straight from someone that was in that meeting.) They even changed the security codes on all the doors at Maple the same day that he left.

The guy wasn't perfect but he sure cared a lot more about his people than anyone in the new team does.