Maresca done well for a period. But he had a joke of a start and a joke of an end.
There's no guarantee he was turning this around. Not without mature signings which the Chelsea board seemingly doesn't look for. They are purely talent acquisition and reselling while also trying to compete at the highest level.
As I said, for that type of model you probably want a stay quiet De Zerbi type. But In the end of the day, they will probably flip coaches like players in a very American way.