Chelsea have changed coaches several times but their performances have not improved. Rather, their performance has deteriorated further. Chelsea's performances have been very poor and erratic this season. This clearly shows that the main reason for Chelsea's poor performance is their players. There is probably an internal conflict between the players. This is why they are not playing well. And so changing coaches again and again cannot be a solution. Chelsea needs to change their entire squad. Chelsea's performance is unlikely to improve unless the players change.
I don't think Graham Potter and Lampard are the proper coaches to make Chelsea competitive in the Premier League, but Pochettino will probably be what is needed to do it. At the moment, Chelsea have a lot of quality players who basically just need guidance and a good strategy to get them to give their best performance. So a change of coach is expected to improve the quality and ability of the team, and I don't think they have to change everything.
Chelsea need a good striker, that's true but they have tough midfielders and defenders. Next season will be a different season for them, I'm sure about that. At least I can hope that Chelsea will return to being competitive in the Premier League even if they don't win the title.
Lampard... I think Chelsea should forget about him like a bad dream and never think about him again, because he basically did nothing good for the team, only made it worse in the table. I'm not saying he did it on purpose or anything like that, it's just that after that incident there are doubts about his coaching competence at all