Mellon was dismissed following the Cod Army's 3-2 defeat to Aldershot in the FA Cup second round - a third consecutive defeat in all competitions.
Yet, with Fleetwood sitting seventh in League Two thanks to the guidance of a man who led them to two promotions in three seasons, Pilley's decision has been widely derided.
He told the Blackpool Gazette: "I have a lot of respect for Micky Mellon. I don't want to go into too much detail on precisely what happened and why - at the moment things are just too raw.
"Suffice to say we felt it was the right time for a change. We had lost our way a little and we needed a change of leadership.
"It is a decision based just upon the way the football club has performed recently. The decision had to be in the best interests of the football club and that is what we have done.
"People will read into it what they will. There were numerous factors we had to take into account but the fact was that a change was needed."
Speaking to BBC Radio Lancashire, Pilley remained ambivalent on the reasons for Mellon being shown the door.
"Ultimately I've got to stand up and be counted and that's the decision I've made," he said. "There are things that go on in businesses that influence decisions and we felt that the time was right.
"He has undoubtedly been a superb manager for Fleetwood over the last four years he's been here. We've gone from being a part-time club at the bottom of the Conference North to a full-time club in the play-offs in League Two, but it's not about the past, it's about the present and the future."
