In 2015 we were playing 3 CB's and 2 wingbacks, so basically 5 defenders, partly to cover for his lack of defending ability. Barzagli and Chiellini were doing all the tackling in those days. This meant we were always 1 midfielder/attacker short. His only positive attribute is the occasional nice long pass which leads to a goal. That's great and he's quite skilled at doing that but a defender needs to be able to defend before anything else. It's no coincidence that his horrible form in Milan and his letting in of goals this season at Juve have been in a 4 man defence, where he actually has to make some meaningful tackles and interventions, something he has never been capable of doing.