The Spanish defender - who joined the London club in 2022 from Brighton and Hove Albion - would have "died" for his former manager and thinks his departure in January following a poor run of form has led to too much uncertainty for the squad.
He told The Athletic: "With Enzo Maresca in charge, we were more stable, because we worked together for 18 months. If you look at our first pre-season with him, there were doubts. You need a process for every player to understand what we need to do. In our last months with Maresca, we played almost by heart. If we changed the system, we knew what we had to do. You need that time.
"Look at Arsenal now, who are fighting for every trophy. They've been with (Mikel) Arteta for almost seven years and they have not won much. But that trust in the project gives rewards.
"We knew what Maresca wanted from us. Winning a title like the Club World Cup also helps, strengthens the bond, and you create great relationships during the celebrations. When a manager gives you that confidence and offers you a platform to fight for titles, you'd die for him.
"The moment Maresca left, it had a big impact on us. These are decisions taken by the club. If you asked me, I would not have made this decision. To make a change like that, the best thing is to wait until the end of the season. You would give everyone, the players and the new manager, time to get ready, have a full pre-season…
"The instability around the club comes from this, in a nutshell. We had a caretaker (former under-21s coach Calum McFarlane) first, then a new manager, with new ideas and no time to work on them. It is what it is."
While Marc thinks new boss Liam Rosenior has handled the squad well and has "good" ideas, he feels the busy playing schedule has left them with little time to try anything new.
He said: "Liam is a very good person and has been great at handling the group, the characters.
"He likes to stay close to us and his football ideas are good, but we don't have the time to train them.
"We train on (playing in) competitive games, because we play every three days and that leaves you with no time to work on the training ground. In this context, it is normal that your plans sometimes don't work out, and then we go through difficult moments."
