Well don't completely disagree with what you're saying just that I think there are mitigating circumstances for the centre backs, and of course its just my opinion but firstly I'd say that because of how weak we have been at full back that this has created added problems for the centre-backs in lots of areas, positional play, covering etc. It was noticeable that the defence as a whole looked better when Vinnie returned yes, but Fernandinho at RB made a huge difference too.
Secondly I think Stones will get better, he had some dodgy moments but he is evolving in a position where he won't be expected to reach his peak for another 5 years. I also think the goalkeeping situation makes a big difference. An element of panic amongst the back line for a lot of the season when Bravo was playing, more assured with Willy.
In other words in my view its not just about Kompany, and therefore I believe that as a group the centre-backs will be much stronger and consistent next season.