Bonnuci, Barzagli and Marchisio were literal shit before Conte came around. Even less established than Alex, Mexes, Rami, let alone an old Nesta and Thiago Silva who was the world's best defender.
While we boasted the great mediocrity of Vucinic as our best attacking player they had Zlatan, Cassano, Robinho, Pato and Inzaghi in the striking positions.
We had dead and finished Pirlo, the supremely mediocre marchisio that hadnt had any decent season until then, and an exciting new signing in vidal. Our bench was the giacherrinis of the world. Milan had Van Bommel, Gattuso, Ambrosini, Muntari, Nocerino, aquilani, flamini, seedorf, and Kevin Prince Boetang in midfield.
There is just no comparing what they had and what we had. Marotta was doing what Galliani is doing today and Conte made an unstoppable force out of it. He resurrected an old veteran who we got on a freebie and built the team around him. He made a permanent old flop like Barzagli into a world class defender (also a freebie). He fixed Bonnucci whom everyone saw as a lost cause and built the best defense in Italy with him, barzagli and chiellini (the only one of them that anyone ever considered talented). He made an attack work without having a single player that was even at cassano's level let alone Ibra's .
Juve's behaviour in the transfer market was similar to the current milan. a bunch of freebies and mediocres + 1 decent signing. Conte made that into the best team in Italy.