Yes we need to sell...but we also need to buy still.
We have one left back
We have no right back
We have one centre half on gvardiol who can play on a high line ( and he is not perfect for it)
We have 2 centre halves who will not be available for most of the season
We have Dias who is not elite level esp in a high line
The club accepted it AFTER the fact. Many were saying it BEFORE it happened.
The above has been there for a year already - especially with Stones and Ake who have had fitness issues for a lot longer than last season. We bought two centre halves nowhere near tge quality (yet) of either of them.
We have had unparalleled success with this squad. We accepted that we held on to some too long after a season decimated by injury. Had the latter not happened, I suspect we would have been title challengers with the same players.
I disagree that the level of injury we had could have been predicted. We also tried to back up Rodri but the player didn't work out - some don't.
Now we are in transition - it happens. We accept that we cannot buy players at the level of peak KDB and Stones, so we buy Cherki and Reis and Bah and Khusanov and Marmoush etc all. This is exciting, not something to fret about.
We won multiple tournaments with people saying Zinchenko and Delph weren't left backs, now they say the same about Nunes and Lewis - I don't agree. We also have Gvardiol and Ake available for left back, not just Ait-Nouri. Many spoke of Mahrez not being good enough; Gundo, Raz and others too. One time in several they get something right, as many did about Phillips.
No defenders in world football can play in a high line without the whole team pressing the opponent, and forwards and midfielders pressing the turnover. We don't yet know our combinations at centre back, who will stay and who will go, so we look forward, excited for the future. I think we have potentially top-drawer defenders, some who have already proven that, but our forward line and midfield is, largely, new and young - the pressing will take time to instill and get to the level it needs to be to play as aggressively as we seem to want to.
You make good points and there is no guarantee that we will get back to the level of unprecedented success we had. That is sport.