The Asian Football Confederation (AFC) decided at their executive committee meeting in Kuala Lumpur on Thursday that only two Australian teams would compete in the Champions League next season, down from three this year.
As third-place finishers in last season's A-League, which concluded in April, Perth will miss out on a berth, and Sage was unhappy after he said he had been told they would be in and had already made provisions to compete in the tournament.
"We hosted a delegation of eight AFC representatives two months ago and were told we were in. And we have been told unofficially that we have been in for the last eight months," Sage told AAP on Friday.
"We had spent up to A$70,000 ($73,100) on a different kit for the ACL, that's an extra player for next season that we could have spent that money on. And we had a new sponsor on board just for the ACL.
"So to be told a week before the draw Australia have lost a spot is bizarre."
The complex procedure to decide on team entries regularly causes friction throughout the Asia zone, with the number of slots being adapted continually due to the emergence of lower ranked nations and the struggles of the established teams, who believe their standing deserves more respect.
AFC executive committee member and FIFA Vice President Prince Ali Bin Al Hussein held a meeting of independent experts in Jordan last month to try to come up with an improved plan but Thursday's announcement by the AFC offered few changes.
In East Asia, Indonesia lost their only slot in the reallocation, with China and South Korea given four direct entries rather than the three and one team starting in the qualifying round that they received this year.
The decision came as a surprise to Sage, who did not realise the number of Australian entries was even up for discussion.
"So that's what gets me, no one has flagged this. I am in a bit of shock at the moment.
"Who makes these decisions and why are they made?"
"The shuffling from one year to the next in determining whether you are in or out doesn't give club owners any confidence. What has the A-League or the FFA done wrong?"
Not helping Perth's cause has been the poor performances of the Australian sides in Asia's premier club tournament with Adelaide United fairing best this year, going down in the quarter-finals to Uzbek side Bunyodkor.
Adelaide made the last 16 in 2010 and also finished runners-up in 2008 but the only other A-League club to make it through the group stages of the tournament were the Newcastle Jets in 2009.
The Central Coast Marriners and the Brisbane Roar will represent Australia next season in the tournament that has been dominated in recent seasons by South Korean sides.