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
Usually, whenever a team makes many changes in a short period of time they need some time to get adapted and the new players should get to know how to work with each other. That's why it's normal to give more time to Pochettino for this season. Because they now have whatever they need. Chelsea got a new coach and many players left the teams which is a reason to say they changed everything and now they just need time to see the result.