Pep must now be realising how much he fucked up in the summer, he bought plenty of attacking players in but did very little for the defensive side. Kompany is simply done and Stones is still a project and going to a top club isn't an easy transition plus the actual CB partnership is an issue as there is no leader there, Otamendi needs more of a leader to bring the best out of him. The fact he's been playing Kolarov at CB is just pathetic.
And don't get me started on the fullbacks they are just wholly inadequate baring Sagna who himself is just solid, they've let the likes of Raphaël Guerreiro now at Dortmund and Djibril Sidibé now at Monaco pass them by plus Riccardo Rodriguez who could have been had on the cheap for under £20mil.
I think he has to take most of the blame for their fortunes because he has neglected key areas and clearly underestimated the PL, he wants to play a certain way and didn't bring in players that could replicate it. I'd say he should take a punt on Jose Fonte at Southampton as he has handed in a transfer request, he would be able to come in and be a leader in the defence. It would be a stop gap but would take Stones out of the firing line and give Otamendi a vet that will lead him, adding to that they badly need at least one full back.