This changes usually takes time and determination and the experience of the manager to make it happen. Does Maresca have that experience and capability to make these changes happen in a short time before the Chelsea management gets frustrated and tired of him. Another important thing is having the right players and right mentality to make it happen.
Young players need challenge, time and patience to complete themselves and by playing with more important roles, bigger pressure, they will improve their mentality stronger with time. It's a common way for all youth players to become star and super star players in football at any club, not only in Chelsea and not only restrict to this player generation that are using by Chelsea.
Currently, it could even be said that Chelsea does not have enough players with long experience. This team just has a lot of potential young players. In order for these players to reach their peak performance, it will take time.
Every young players need time to grow up, sharpen their skills and get familiar with more important tasks and bigger pressure too. They need time to become a better versions of themselves and to be able to carry bigger tasks. Chelsea are aiming at building up a young squad which can help them to play competitively in next 10 years. This is a big and ambitious plan from Chelsea but players they bought look are not too promising to complete this plan well.
Enzo Maresca may slowly be able to take Chelsea in a better direction. But I don't think so soon. Because Enzo's task is quite difficult. because he definitely realizes that as a coach at a club that relies on young players, the coach must have a different touch in the training methods applied to bring out the potential of the young players so that it is maximized when it is revealed.
Maresca is experiencing his job at a first big and rich club in his coach career. It's quite not familiar feeling and huge pressure for Maresca and he needs time to adapt to these big changes. He has bigger budget to spend for player transfers, better player resource but he also has bigger pressure from the boss. At big clubs like Chelsea, pressure is huge and they are not familiar with staying low on ranking table. Moreover, with big budget spent for player transfers and salary, boss doesn't want to wait for a long time to see success. A streak of bad results means big risk of losing your job and this pressure is on shoulders of Maresca as well as in his mind.