Chelsea's poor performance is mainly due to some bad management decisions. It takes a long time for a new coach to stabilize a team. Stabilizing such a troubled team is no easy task for any coach. But the Chelsea management wants a quick improvement. This is not possible at all.
I don’t blame any of their coaches they signed or any player for their poor performance, in fact, I am putting the blame on the management and the owners for lacking patience with managers just because of the money they blindly spent on signing players and because they want quick results.
Take Arsenal for example; they spent some money for players, but they gave the manager some time to build his team, now Arteta is doing well since he was able to build his team and can now perform very well in all competitions. Despite Arteta not winning trophies, Arsenal management were patient, but I am sure they will win title next season.
Yeah it depends on which way we look at it, while I think both have an impact. Management wants to see team performance improve quickly while they forget everything needs a process, we will see what their steps are in the next season.