Unlike last week's road loss to the Western Sydney Wanderers by the same scoreline, Mulvey said the performance against the Phoenix was sub-par.
He is planning changes and hinted his selections will be skewed towards building a brighter future for a club which appears on track already to secure a third wooden spoon in four seasons.
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Goalkeeper Adam Pearce made his A-League debut against Wellington and forward Jordan Murray his first start. Mulvey later took interest in how midfielder Mario Shabow and striker Josh MacDonald performed off the bench. All four players are aged under 24.
"You don't want to throw them in when things are not going right but they deserve an opportunity now and I think we need to look at that," Mulvey said.
"I've got a history in the A-League - with Gold Coast United (2010-12) - of playing a lot of young players."
Mulvey was impressed by 21-year-old Pearce, a decade younger than 12-season veteran gloveman Ben Kennedy, who was unavailable with a leg injury.
Kennedy may find it hard to oust the 1.98m Pearce when fit again.
"Adam's got a great physique and has a great future in the game. He needs to be given an opportunity to play a little bit more."
It's looming as a long season for Mulvey and the Mariners.Credit:AAP
Upon arriving at the Mariners this year, former Brisbane Roar coach Mulvey said he identified a weakness in the club's development program.
He was heartened a number of good youth coaches have been hired, believing that is the key to Central Coast returning as an A-League force and avoiding the chop when promotion-relegation is eventually introduced.
"In five or six years there will be relegation," Mulvey said.
"We need to develop our own players because we weren't producing what we were producing six, seven, eight years ago. So we've addressed that."
AAP