The highly regarded coach was dismissed on Wednesday in something of a shock following a reported disagreement with club owner Peter Lim.
Marcelino had been at Valencia for two seasons and guided them to back-to-back fourth-place finishes in LaLiga, a feat many see as overachievement given the club's woes over the past decade.
On top of strong league campaigns, Marcelino also guided Valencia to their first piece of silverware in 11 years last term, beating Barcelona 2-1 to lift the Copa del Rey.
But it was that success, Marcelino claims, which ultimately cost him his job, with the former Villarreal boss suggesting he went against the board's wishes in concentrating on a competition he believes they deemed to be "minor".
"I am absolutely sure that the trigger for this situation was the Copa del Rey," he told a news conference on Friday.
"During the season, we received direct and indirect messages that we had to discount it [the Copa]. The fans wanted to fight for it and the players too, and they had the conviction to win it. The coaching staff wanted to fight and win the Copa.
"They didn't tell me why they didn't want the Copa, only that it was a minor tournament and that I could be putting the main goal [Champions League qualification] at risk. Winning the Copa was the trigger for this situation.
"We did not receive congratulations in Seville [after the Copa final] from the owner [Lim]. When I went to Singapore [for a meeting with Lim and Anil Murthy, club president], I was congratulated for qualifying for the Champions League, not for winning the Copa."
Former Barca and Real Madrid midfielder Albert Celades was chosen as the surprise replacement for Marcelino, despite receiving significant criticism for negative tactics and lacking a style of play when he was in charge of the Spain Under-21s until his resignation last year.
But Marcelino hopes the fans get behind the man who was Julen Lopetegui's assistant at Real Madrid.
"You know Valencia is complicated for coaches," he said. "I was fortunate that the fans received me warmly.
"I am proud to leave two years later with the same kind of acceptance, and I won't forget that. I have been really happy in Valencia and lived unforgettable moments.
"I hope the people now support Celades. I wish him the best of luck."