I seen around 6-7 games this season, putting in occasional good cross to get assist in attacking width side is not all thats required from an LB. I'm not sure what you are seeing, but I dont see much of a talent when I seen him, young and raw, but his abilities dont exactly scream come and start for Juve, the opposite, seems rather limited. It would be significant downgrade to sell Sandro and have him as starter as it is currently. It is one thing to want to replace Sandro, but if you are aiming this low with replacements (Pellegrini or likes of Emerson), then its no point doing it. Only LB in Serie A I would wanna replace Sandro with is Theo Hernandez. Or Gosens if he counts as LB and not LWB.