The Roar have already launched a worldwide search for Berisha's replacement after the former Golden Boot winner signed with Melbourne Victory for 2014-15.
But some of their fans have not been so quick to accept the high-profile move.
Roar will have an early glimpse of life without their feisty talisman when they host Wellington Phoenix on Friday – a match Berisha will miss through suspension.
"I think Roar fans will agree with me that we have shown some real quality when Besart has not been available and proven that there is light at the end of the tunnel – it's a beaming light," Mulvey said.
Mulvey said the team had also been pragmatic about Besart's departure.
"We have a great relationship. At the end of the season we will have a hug and hope to do it with some silverware," Mulvey said.
"We tried to convince him as much as we could but money talks.
"He has looked me in the eyes and promised to give 100 per cent for the Roar for the rest of the season – I believe that and I am sure the fans will as well.
"He wants another championship and he knows he has a role to play.
"The team is so united now. They have accepted Besart's decision and they have moved on."
League leaders Roar will welcom back Corey Brown and James Donachie (Australian under-22 side) but Ivan Franjic (side strain), Matt McKay (leg) and Liam Miller (hamstring) are under fitness clouds.
