This is just another example of the owners not understanding football isn't it? They've just seen he's managed to win the Championship with Leicester and assumed he must be a good manager? Not taking into account that Leicester should have absolutely won that league regardless of their manager, and it probably ended up closer than it ever should have been.
It's like Kompany and Burnley. Blitz The Championship playing like City but only because they've got better players and a far bigger budget than almost everyone else in the league. Then Burnley come up and play the same way and get embarrassed every week (despite spending a lot more than the other promoted teams).
But is Chelsea the club to even play that slow, possession style anyway? Or more to the point given the time to make it work like Pep and Arteta were. It took Arteta 2-3 seasons to get it right.
When they've done well it's mostly been built on more defensive and counter attacking tactics like Mourinho (x2), Tuchel and Conte.