I don't know if some of you know the inner workings behind closed doors of businesses, and football is clearly a business. The line between "fired" and "resigned" can be a very narrow one. I've been managing departments at businesses for years... I know this firsthand.
The one thing that puts this in favor of Juve's board is that they clearly seem surprised by DD's move. That said, there are volumes to be written on the topic of "managing out" -- i.e., you create an environment of failure, conflict, or misery for someone else where they have little choice but to leave.
I don't believe the Juve board went that far. But the fact that DD did resign just at the beginning of a possible Serie A campaign -- after what he personally went through and fumed about when Capello was first named coach and what he did to take on a Serie B club -- makes me terribly suspicious that something stinks really bad in the Juve board. Personal politics, bad ideas about football, what have you. This is a sign of dysfunction.