Postecoglou, who took over when Holger Osieck was sacked eight months before the 2014 World Cup, only hinted at the reasons for his departure on Wednesday but it might be that Australia's laboured qualification played a part.
Missing out on a direct ticket to their fourth straight World Cup finals prompted a barrage of criticism of the coach and the playoff victories over Syria and Honduras did little to ease fears that Australia are just not that good.
Postecoglou overhauled an ageing squad at the start of his reign and his young side performed creditably in Brazil, even if they lost all three matches to Chile, the Netherlands and Spain, before going on to win the 2015 Asian Cup.
The departing coach always felt that it was no good just getting to the World Cup, the team had to play a style of football that would enable them compete on the biggest stage.
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To that end, he made the switch to a three-man defence for the final round of Asian qualifying, a move that was to provide much ammunition to his critics amid whispers that the players were uncomfortable with the formation.
The main problem the new coach will have to wrangle with when he is appointed is not at the back, however, but who is going to score the goals.
Tim Cahill will be 38 by the time his fourth World Cup comes around but Australia needed his 49th and 50th international goals to get past Syria, while skipper Mile Jedinak notched a two-penalty hat-trick to win the Honduras tie.
Those two aside, there is plenty of attacking talent in the Socceroos squad with players like Aaron Mooy, Tom Rogic, Robbie Kruse and the fast improving Mathew Leckie but they are creators rather than finishers.
Australian teams will always offer physicality and a positive mental attitude but without goals, they might struggle in Russia whoever they draw.
(Editing by Amlan Chakraborty)
