Don't think he benefited from being next to Kompany much at all, his best period was always alongside Stones where he really lead the defence.
He's a good defender with one glaring weakness - pace - but he's always given 100%, always played through all sort of small injuries when we needed him. He's one of the few players in recent times who I think leaves the club without any mixed feeling over if he could have been better or if he gave everything he could to the club.
I assume Porto play a deeper line of defence as they have 37 year old Pepe, and I think he'll do really well there.