It's not like Juventus is buying a replacement for Chiellini. He would be a 3/4 choice defender and being young and having Chiellini next to him could improve.
To have some depth With natural and good left winger his only responsibility would be to defend. Anyway, we do not have a pure left winger and will probably won't buy him so the discussion is useless. I completely agree he cannot be used on the left with current wingers.
But that "more experienced" CB will be just a bench player and our back line will be consisted of 3 youngsters+Chiellini, one of which will be played completely out of position.
I see 0% sense in buying Bocchetti for the left side, if we play 4-4-2 or any formation with 4 defenders.
Don't forget we play on 3 fronts so every top team should have 3 quality CBs. Legro should simply be our 4th choice, while we should aim for somebody much better IMO. I was never impressed with this guy...He wouldn't be bad but surely we can find better.
IMO we should look for Lugano and Burdisso instead.
If we had somebody like Elia or Giovinco who isn't all that defensively then Bocchetti could be an alright choice but since we already have Pepe for the left who is amazing at tracking back we should have a more offensive alternative as LB.
It's a position with lot of yellow cards and you cannot rule out injuries. I do not think that a so called 3 choice defender would actually be a bench player. More realistic is that all 3 of them would have almost same number of games.