Chelsea have since struggled to adapt with the huge changes to personnel and pochettino has not been able to galvanize the squad that was already on a freefall having work under Thomas tuchel, Graham potter and frank Lampard last season and also with the sweeping changes on the front of transfer I think Chelsea are still coming to terms with pochettinos method which notoriously demanding and require high fitness
It is true that Chelsea has had difficulty adapting to major changes in personnel. In my opinion, things like this are very normal because changing teams can affect the dynamics and cohesiveness within the squad. Meanwhile, Pochettino as a new manager also needs time to understand the characteristics and potential of each player. Of course, the big challenge for Pochettino is to raise the enthusiasm and performance of the squad after a tumultuous season. However, you need to remember that each manager has a different style and philosophy so it takes time to implement them optimally.