This is a very tough task where Pochettino has to coach Chelsea when it is in its worst phase.
With the replacement of several players it might be easier for Pochettino to improve Chelsea's performance but the question is whether Chelsea can spend a larger amount of money to be able to transfer players. But if they are willing to sell some players and the proceeds from the trade are used to buy other players then Chelsea can save a little on spending on player transfers.
I don't even understand the way young players wants to leave Chelsea, is it that they don't have faith in the club anymore or they don't want to work with the new manager Mauricio Pochettino. Kai Havertz, Christian Pulisic, Mason Mount, Mendy have all been tipped to leave Chelsea and these are promising players and should be part of the team's project. No disrespect but old players like Thiago Silver and the likes should be packing their bags but the reverse is the case. I know Chelsea had some good additions come in during the January transfer like Wesley Fofana, Mykhailo Mudryk, Enzo Fernandez etc. but they management needs to do all they can to make sure that most of these players don't leave.
Maybe this happened because there were offers from other clubs that were more promising and Chelsea's own management did not defend them by offering a contract extension or slightly increasing the agreed contract.
If some players are not able to give maximum results then just let them leave Chelsea so that Chelsea can take other players who are more dominant but for players with potential Chelsea still have to keep them.
I'm sure if Pochettino manages to change Chelsea next season and at least make Chelsea Runer Up or even a champion then Pochettino himself can have achievements and is also known as a very great coach because he brought big changes to Chelsea.