To change 180 is very difficult in my opinion, unless Chelsea have enough resources to do it, both in management and from the quality of their players, and Chelsea must restore their reputation to become one of the teams that are resolved in the league as before, motivation and Development of the ability of the players must continue to be done by working double if you want to make changes quickly.
In fact, Chelsea have pretty good quality players and so far Chelsea have only had problems with the coach, so this season they have played poorly.
If only Chelsea had a coach who could take advantage of several players and also improve the skills of his players, maybe Chelsea could still compete with other teams in the Premier League this season.
I'm sure Chelsea can get up and play well next season but not fast because they just signed a contract with a new coach so they need more adaptation to be able to assess and correct some of the mistakes that have made Chelsea slump.
I was just about to write the coaching factor but you beat me to it. I saw somewhere else on the internet that saying City is successful because they have arab owners and president. This is obviously not true. There are a lot teams that have arab capital right now but nobody is this successful, including PSG. City is on another level mostly because Pep Guardiola. He was first great in Barça, then Bayern and now immensely successful in City. Pep factor is maybe the most important in City's success. In my opinion Chelsea is also on a good way, they just need time and adaptation, then they will be much more successful.