The Blues have been through a lot of change over the past few years and even this summer.
While the club focuses on selling players behind the scenes, Maresca feels he has a settled starting 11 and squad depth.
He told reporters: "It's already the first 11 we want, already the squad that we want but the first 11 we had against City is not always going to be the same for the season. I repeat again: I am not working with 42 players.
"At this moment, I am working with 21 players. Today's session is with 20 players. Yesterday's session was with 21. But the other 15 or 20, they are training apart. In the USA, we had 26 or 27 players.
"Chelsea players, yes, 42 or 43, sure, but they are not working with me every day. I don't see them so it's not a mess like it looks from outside. Absolutely not."