I think Pep will have to have 4 categories of player...
1) Who is inadequate - sell
2) Who is adequate - keep, but actively start looking for upgrades
3) Who is nearing end of life - keep, but actively start scouting for replacements
4) Highly capable, and no need to replace
We have quite a few players in categories 1 & 2 (Ota,Mangala,Clichy,Kolarov,Navas,Bony, Sterling,Nasri,Delph,Fernandinho) - the question is which of those Pep feels he accept in improve and which he can't.
Many of our stalwarts - Kompany, Zab, Silva, Yaya are in category 3.
Arguably only Hart, Aguero and KdB are in category 4
When laid out like this, there's quite a lot of work to be done (or certainly lots of scope for improvement). Hand on heart, most of our players are not at the very high end of European football, they're at the higher end of PL football only, and of those that are high end, they're getting on.
We all debate about the future prospects of younger players like Nacho and Sterling, but if Pep is tasked with winning PL and CL and if here for 3 years, then we have to ask 'are they likely to be CL winning material in the next 2-3 years'?'
I am seriously hoping Pep believes he can coach a lot of players into being significantly better - e.g. Sterling, Delph, Ota, Mangala, Fernando otherwise he's got a hell of a job on his hands, because hand on heart, I think there's only Hart, Aguero and KdB that would pique the interests of Europe's very best teams, and maybe they'd take a punt on Sterling, but I'm not convinced.