Aye, it's a bit weird. I was just making an observation that we have a young back line with minimal experienced cover, and one of the best CB's of the last 20 years has gone to Berlin for next to nothing. Obviously you wouldn't pick Boncucci to play in a high line - even in his prime he wasn't exactly mobile, but I would have him sharing his experience in training and coming on at 1-0 up in the last 10 minutes if minute to close out a win if we're penned in.
One important consideration is that Bonucci has only ever had 1 red for Juve - which is testament to the fact that he very much knows how to defend without making rash tackles.
All of which is academic because he's gone elsewhere, and quite possibly because he wants to remain a starter.