Victory were smashed 6-1 on Sunday night by Sydney FC, their worst loss in 14 A-League seasons.

The nature of the devastating loss is sure to have ramifications during the long off-season.

"What happened? Everything happened," Valeri told AAP.

"Everything happened that we didn't want to happen, that we spoke about not happening.

"It was hard to be involved in and the boys are absolutely gutted.

"It's going to require a bit of a self reflection process, going through it and fixing the problems where we went wrong because it is unacceptable."

While the margin was mighty, the fact remains that Victory were within one match of returning to the grand final.

They finished just two points behind Sydney FC after the regular season and enjoyed wins over every A-League side.

Perhaps that's why there's some prevarication about how big Victory's response needs to be - and who should lead it.

Muscat was a devastated figure after the match - the heaviest defeat of his coaching career.

He made the most cursory of appearances at Monday night's Dolan Warren Awards night in Sydney, slipping in just prior to the ceremony and dashing out shortly after.

There can be no doubt as to Muscat's ability as manager.

In five full seasons in charge he has never failed to make the finals and lifted four trophies; two titles, one premiership and an FFA Cup.

He is contracted for another season and enjoys a close bond with chairman Anthony Di Pietro.

The magnitude of the loss has still brought his future into question, though Valeri doesn't feel the 45-year-old club legend has a case to answer.

"Musky is a top coach. He's young, he's got a hunger, he leaves no stone unturned," he said.

"We're suffering, but only there's no one suffering more than Musky.

"He wears his heart on his suit. He puts everything, his heart and soul, into the club.

"He's contracted, you know, I hope he stays because I know that he'll turn this around."

After pulling off the recruitment coups of Keisuke Honda and Ola Toivonen this season, and before that Besart Berisha, Terry Antonis and Valeri, the retiring skipper backed Muscat to revamp his squad again.

"Musky can do it. The recruitment process the club has set up is fantastic," he said.

"With the players we've brought in (this season), I'm feeling a bit heartbroken about that I'm talking about it because with the players we had, it would have been good to put more of a fight against Sydney."

Australian Associated Press