Glory has already started planning for next season after crashing to the bottom of the A-league with no hope of making the finals.
When Hierro made it known via The World Game in February that he was willing to coach in Australia and bring striker Raul Gonzales with him as a marquee player, Glory made enquiries.
At the time the club was reeling from the shock sacking of Alistair Edwards and was in the hands of interim coach Kenny Lowe.
The club dropped its approach when the World Cup star's representatives failed to give Perth enough information about what Hierro would do at the club if he got the job.
"Yes, the club was interested and made enquiries with his agents," Sage said.
"But they never got back to us on time and when they did, they did not give us enough details so the process stopped. The application was incomplete.
"All the candidates have put together a plan and we'll go from there."
Glory has since set up an independent six-member commission headed by former Australia goalkeeper Mark Bosnich with the job of vetting the applications for the position.
"You might have heard about Bosnich ... he's a well respected guy," Sage said.
"We had about 50 applications for the job and we have narrowed them down to six.
"We have an independent body looking after the process.
"You should have football people picking football coaches and for this reason I'm not on the committee.
"How would I know how a coach should approach things?
"I trust those people to put in a recommendation and then it's up to me and the board to make a decision."