The bigger problem with coaching a crisis-prone club like Chelsea is that, the management won't give the coach enough time to build the club back through the recovery stage until they can stand on their feet rather the club owners will want the new coach to start performing miracles and delivers the winning right away.
But the process of reviving a club that has gone through a series of crises and poor performance throughout history is not overnight magic, it requires long-term work and preparation that position the club for a better fit to be able to deliver quality results in the long term
That's right, most club owners can't wait to get their money back. Almost all wealthy clubs will demand a coach to be able to realize his ambitions as quickly as possible, it is not impossible to do so but it takes time to make it happen. In Roman Abramivich ownership history, we can see how many coaches were fired, and star players were recruited. But in reality, it was interim coach Roberto Di Matteo who had greater luck.
I think Chelsea can come back to be the best in EPL and UCL, but Owners and Fans have to be patient.