It's actually quite easy to see what is happening to Chelsea at the moment and we need to ask Chelsea management, who several times brought in players at very high prices but did not have the quality of talent commensurate with the player's price.
It's simple but we very rarely understand this problem and in fact it is an obstacle for Chelsea to return to the way it was before and on the one hand seeing Chelsea in a bad condition like this is actually very regretful because after all Chelsea is actually one of the popular teams in the EPL but now it's like become a mediocre team.
Pochettino does not have any faults because he is only a coach who is given the responsibility to improve the quality of Chelsea players' performance, even though he has tried in whatever way he can, he still seems to have difficulties and in my opinion, if Pochettino really wants to improve the players' performance, he has to make a major overhaul of Chelsea players and try to bring in more quality players.
Badiashile and Thiago Silva might be good options in defense but to be honest I doubt Badiashile.