Respect and can understand this opinion but imo his role wasn't simply to defend as a CB so it's unfair to compare him to Barzagli and Chiellini who as you imply were two of the best ever, both playing in their prime.
Leo wasn't a pure playmaker either, it was his unique mix of the two that facilitated us playing Pirlo or Pjanic without the need for a Gattuso constantly creating space in the centre. Bonucci gave Khedira, Pogba, Vidal or Marchisio more freedom to move further up the pitch, because simply marking Pirlo wasn't enough to negate our game plan because Bonehead gave him an option.
Every piece of those great teams we had had their own important roles to play, and imo Bonucci was no different. I still hate the cunt mind you.