The Marinos have been a team remade under the one-time South Melbourne, Brisbane Roar and Melbourne Victory boss, who took over at the start of the 2018 season.
They haven’t won a title since going back-to-back in 2003 and 2004, and they haven’t picked up a trophy since their Emperors Cup win of 2013.
It’s not as if they were foundering before Postecoglou took over: under the four-year reign of his predecessor, Frenchman Erick Mombaerts, now the head coach at Melbourne City. They had trod water before improving into fifth place on the table the year before Postecoglou took the hot seat.
But he has breathed new life into the club and after initially finishing 12th in the first year of his tenure, has had them challenging for top spot all season.
If he can win the title it would be a remarkable achievement for the independent-minded Postecoglou, a man whose departure from the Australian national team still frames much of the narrative, at least in this country, about his footballing achievements.
When he found himself under an unprecedented amount of criticism late in the 2018 World Cup campaign and realised that his long term vision for Australian teams – to build up an attacking, risk taking culture which never took a backward step and believed in itself – was not shared by those he believed should have had his back, he decided to find a fresh challenge.
Plenty – including this writer – found fault with the manner of his departure and the lack of clarity at the time, given the circumstances. A handful of his confidants were given more details, but for most in the media and the public there seemed little clear explanation and he certainly didn’t feel compelled to elaborate.
It was a great shock to the football public to lose the man who had won the Asian Cup in 2015 and inspired a generation of Australian players just seven months out from the biggest sporting tournament in the world.
But he has always been a man who is prepared to march to the beat of a different drum so his current success should not come as a surprise.
I remember speaking to him in the foyer of a hotel in Rio De Janeiro in January 2000 as his team of part-timers from South Melbourne prepared to take on the likes of Vasco Da Gama, a Brazilian powerhouse, and Manchester United in the inaugural World Club championship.
Postecoglou was still only 34 then and had not all that long ceased playing, but he was not – publicly at least – perturbed at the prospect of taking on the likes of Sir Alex Ferguson, the then United manager, in any tactical battle.
It’s an attitude he has adopted ever since: his view is that you might as well go down with your own ideas and approach, as adopting someone else’s and failing with those still won’t save you.
Maybe Postecoglou is better suited to the season long test of league football, where he can build relationships with players and develop tactical strategy over a lengthy period.
Maybe he is, as he said in a radio interview this week, ”freer” than he has been before.
But he would not be having this success were he not a top flight coach, irrespective of those other factors.
His performance in Japan may lead him to better known leagues and bigger clubs, but who knows where this enigmatic character might next pitch up.
Given his commitment to the Australian game – as anyone who read his book, published while he was Socceroos coach would know – it would perhaps be fitting if he eventually returned to this country, not as national team boss but as FFA chairman, where he could maybe shape things more in his own image.
His achievements in Japan illustrates what a loss to the Australian game it has been not to have someone with his knowledge and ability to act as a catalyst for change still involved.
Michael Lynch is The Age’s chief soccer reporter and also reports on motor sport and horseracing