When you want to create a big team, you don't sell your only classy players. Creating a great team is a buying process, so you'll have to put the money on the table. Sell Chiellini would gave us, at best, 15M to another squad player (since ~15 should be reserved for a good CB) and we'd lost a great player (regardless you think he is or not) for two good ones.
Chiellini don't know how to pass? For god sake, he is a CB. And he is meaningly above average in that chapter (for his position, ofc). If you mean long pass, then I just don't want Juve playing that shitty kind of game. About positioning, he rectifies that with some pace and agressivity. A right partner can help, too. Two equal CB, where their mainly quality is being usually consistent, will be fucked against the great strikers.
But let's sell Buffon, Chiellini, Melo and release Del Piero to earn funds and create a 'great' team.