Enzo Maresca has given Robert Sanchez the chance to prove his quality, but he has failed to live up to the coach's expectations. The decision taken by Enzo Maresca is very reasonable and previously Hansi Flick had done the same thing to Inaki Pena, now he is more trusting the main goalkeeper position to Szczesny.
Chelsea certainly won't be short of players if Robert Sanchez chooses to leave the club, there are still plenty of other goalkeepers who can be relied on to strengthen the team.
For a goalkeeper, of course, it will not be difficult for any team to find a replacement if their old goalkeeper leaves the team, but the team also needs to see a goalkeeper who has such strong reflexes because a team like Chelsea is a team that often competes in the best place so that the goalkeeper should not be taken carelessly. Although this can still be fixed very well when the goalkeeper is really trained routinely to become the best goalkeeper on the team and Enzo Maresca is also someone who is able to read the character of a player like a goalkeeper before he uses him as the main goalkeeper at Chelsea.
Enzo Maresca is a talented manager; he knows how to fix his team that can give him the result he wants. As for the goalkeeper, I know he will know how to make things possible for the team to be good again. He can get a goalkeeper and train him as he wants to make him better of his choice, and then house him as the main goalkeeper.
although sometimes they can still hire someone who is already an experienced goalkeeper that can be able to do everything; there is no need for too much training, as he already has the experience Enzo wants, but let's see, because I know Robert Sanchez already failed; he was given enough time, but he did not meet up to the expectations of the coach, just as you said.