If every season Chelsea always replaces their old coach with a new coach, of course Chelsea will always find it difficult to find more wins in every new season they live. Because every new coach is different in the way they train players and also different in how they read the players' character, so changing coaches in each season will actually have a big influence on the good and bad of the team's performance. Although dominantly it might be worse if the coach was not experienced enough in coaching an English team like Chelsea.
Its difficult for Chelsea has consistency performance if replacing head coach every season and need new tactician adopted well by their players with difference head coach. Pochettino have sack from his position after reaching mutual contract and actually its bad impact for Chelsea ha good trend performance after success finishing on 6th standings position with potential playing in Europe League next season. For next season, under new head coach will adopt new tactician and Chelsea's players must adopt well with difference tactician if won't difficult return back to winning trend.
Chelsea's management should change their bad habit by sacking manager every season, its bad for long term perform and players need new adaption with new head coach every season with formation will drastically change under difference head coach.