The last time Chelsea was in 11th place was probably more than 20 years ago. Since Abramovich bought Chelsea they have been constantly at the top of the standings, winning championships and the Champions League, what is happening to Chelsea now is a setback of years and the loss of the team's potential.
I remember quite well when they finished 10th the season right after winning the title under Mourinho, that was not even 10 years ago, when Leicester took the crown. It doesn't even tell the full story as they were at some point even in 17th place, worse than they ever did this season.
That was the team with player of the season (Hazard), so yeah it was pretty dire then, and they clambered right out of it.
I'd count on them getting right back on top, as soon as they fix main issues and stop trying to buy the title.