I expect to see Pochettino help Chelsea to be on top of the table but that's not going to be easy for them in their current situation that's why we should wait and see how Pochettino is going to rebuild this team because the Chelsea we see right now is completely broken and this will take some time for Pochettino to do some reworks with his team and make them have better performance than we saw in the last season.
Worst case scenario, i think Pochettino should be able to get Chelsea to fight for an Europa league position because even Champions league football is far fetched (atleast on paper).
Pochettino can use the pre-season to test how strong his team is, he needs to find the right formation to bring Chelsea to the top four.
Since last season PSG was totally unstable. So why coach Pochettino has to do a completely new job if he wants to perform well in the next season. There have been several changes to Chelsea's squad. Pochettino needs to help the players adapt to the team. Also, if the match strategy is not good, I don't expect Chelsea's performance to improve. Pochettino has a new challenge ahead of him with everything. But we are not sure if Pochettino will succeed. With enough support from the Chelsea players, Pochettino is expected to stabilize the Chelsea team.