I think a lot of people underestimate the role of injuries. After Kompany retired our first choice CBs were supposed to be Laporte and Stones. From 12 months between them they have missed 9, and that might be generous. Otamendi has seriously regressed and Dinho isn't a CB in the first place, apart from being 34 y.o. In addition to that Mendy has struggled again, Zinch was injured 2 months too, Angelino wasn't good. There have been also many small injuries, Raz had to play many games because Sane was out...
Thought Pep had to use more often 3 at the back and experiment with Kyle at CB. He has his reasons to prefer other options though. Shit seasons happen. We can still rescue this one and make it a big success story but are the energy and determination of the players there to do it?