Postecoglou, currently head coach of Scottish Premiership leaders Celtic, was at the Socceroos’ helm when they won the continental title for the first time since Australia joined the Asian Football Confederation in 2006.
Victory over South Korea in front of a sold-out Stadium Australia looked set to give football – often seen as one of the country’s lesser sporting codes – a major boost, only for the honeymoon period to be shortlived.
“The reason I was obsessed with winning the Asian Cup was because I thought that could be a watershed moment for Australian football because I think winning is everything,” Postecoglou told Stan Sports.
“I thought (that) would then give me the power and also allow me the opportunity and (get) us as a nation to stand up and say, ‘OK, this is who we are now. We want to be the dominant side in our region,’ which is not easy.
“A week after winning the Asian Cup, I just felt really flat because it didn’t have the impact I thought it would.”
A disillusioned Postecoglou stood down from the role after qualifying Australia for the 2018 World Cup finals, with Bert van Marwijk stepping in to lead the team in Russia.
Graham Arnold has since taken over as coach and his Socceroos were eliminated from the 2019 Asian Cup at the quarter-finals stage before struggling to land one of the continent’s automatic berths at this year’s World Cup.
With two games remaining Australia are third in Group B of Asia’s preliminaries, with only the top two finishers guaranteed to advance to the finals.
“I still don’t think we’ve capitalised on what I thought should have been,” said Postecoglou.
“We’ve been to four Asian Cups and we’ve only won one, so it’s not like we can say it’s easy to win. It’s not like that. And it could be another four before we win it again.
“That was going to be my benchmark – to say from now on, don’t accept anything less than winning the Asian Cup every time, qualifying for the World Cup and being the number one nation in Asia.
“And I couldn’t find that golden key to open that up.”