Last season when Chelsea hired a new manager in half of the season, they went on to win at least 2 trophies including Champions League but this season have been one to forget for them. They already lost 2 trophies to Liverpool this season and they will end the season with no trophy.
It is not a new thing, except at Manchester United, for a manager going to a new top club to perform better than the previous manager. That was what Tuchel banked on by winning those trophies. This season, the other clubs now understand how Chelsea play and that has contributed to the team not winning till now.