because I saw several Chelsea players who seemed to be getting bored or lazy to use their strong performance in every game. so it's true that it's a waste to change coaches a few times but Chelsea's players don't have the consistency to have the desire to win any trophies.
The points difference of Chelsea with the other top clubs are far, that's why they're not trying harder because they're wouldn't get anything. Lack of chemistry with the sudden many players change were ruin Chelsea performance. There's always a difference when you're playing with your best friend and new player, you will feel awkward and not really trust with each other. It's really hard for midfielder to trust which striker when there's no striker better to score a goal.