The new coach doesn't matter it still depends on players that are playing, this is also a gradual process. Between Chelsea and Real Madrid now the strong team among them is Madrid, if Chelsea win it will be a shock to me and if Madrid loss is going to be a surprise to me. Madrid is far stronger than Chelsea now, is going to be to early for the coach to win Madrid due the performance of the team, they are doing excellently now.
The coach matters a lot. There are some things that will help the team to win the game
1 team compositions
2 strategy
3 decision making
The coach will be also deciding which player that must be substituted or not. This really giving impact the performance of the club. it does not always depend on the players. The players need someone who can create a good strategy that is used to defeat its opponent.
I think that it's really wrong if the game was depending only on the players. The players always need someone who will able to guide the team to the right track