I think for them to get back in the Big 6 status, Todd Boehly has to ensure more trust in the manager and the players and let them do their things. If they are given time, things will start going their way more often. The manager that they have right now is great and had a great season with Leicester. He needs to be given enough time, and they will return to who they were 2-3 years back.
Chelsea actually have players that are capable of bringing result to that club but unfortunately it’s surprising to see how some of these players performed excellently in their previous clubs but their performance decline after joining Chelsea. I don’t know if it’s the couch fault or the entire system about the club. There is a saying that Rome was not built in one day. It will definitely take Chelsea some time to rebuild the team to be on their former track but do they have that time to exercise patience. Other clubs can tolerate a manager even in their trying time but Chelsea doesn’t belong to that category despite it is not bringing them result.
You have answered the question yourself at the bottom of your reply that all these problems occurred with management or Chelsea president Todd Boehly who did not give much time to any coach who wanted to build the club even stronger.
A more obvious example is Pochettino's dismissal when this coach managed to make a very good contribution at the end of the season but unfortunately the coach was fired without any reason.
Meanwhile, all clubs need a long time to achieve a bright future to get a prestigious title like Manchester City and other clubs do, but Todd Boehly doesn't seem to have that experience so he wants something quick to get and is thinking about changing coaches at any time. can make a difference to the club.
Currently Enzo Maresca has been chosen as the new coach and this is the right choice for Todd Boehly but it depends on whether he will be retained later when he experiences a little problem and if he is retained, Chelsea will return to its glory days but if not, Chelsea will continue to experience the same thing.