Chelsea absolutely can do that, when they stop believing in a manager. When the players also stop believing and the play is only going downhill for a long time now, they absolutely should.
Btw he isn't really near the top % wise. Not near the bottom either though. But I feel like many were well happy with Avram Grant and Sarri not keeping their job. Both with higher win rates. Even Mourinho the second time around, is only 1% off Tuchels win percentage. The first time he was here, he was well well above obviously.
On top of not being impressive on the field, he is also a figure that always ends up fighting with the board/management.