#4 Other Competitors
Chelsea are a club who have developed their sucess on sacking managers and replacing them. If a manager cannot achieve his targets, he will be sacked as soon as possible. Despite this they have continued to win trophies.
Such a thing may have worked in the past but now things may not work like that. Pep Gurdiola's Man City already look unbeatable and they will strenghten again this season. Both Jurgen Klopp's Liverpool and Mauricio Pochettino's Tottenham have a well established squad. Arsenal and Manchester United will also strengthen in the summer under their managers.
For the time being all top teams in the Premier League have a manager and a squad who know each other well and this will help them next season.
It should be considered that the Premier League is more competitive than ever before. A team and a manager who know each other well would surely be a bonus for any team. It is highly likely that Chelsea will improve next season under Sarri and then teams will find it difficult to win against them.
For a new manager to come in he will first have to understand his squad then the league, should he be a fresh import to the English top flight. After this he will have to understand how he has to make his team play so that they play consistently and win trophies.