Coached by Dutchman Bert van Marwijk, the green and gold were the only nation not to score from open play at the tournament as they picked up just one point from their three group games.
Having implemented an attacking philosophy during qualifying, Postecoglou admits it was disappointing to see the Socceroos fail to back themselves against the best.
"I always fancied us, whoever we played, we’d have a crack,’’ Postecoglou told The Herald Sun.
"I didn’t like the approach. People again didn’t like my opinion, because it flew in the face of a well-credentialed overseas coach.
"I never questioned the coach’s credentials – fantastic record. That doesn’t mean I agree with his approach. I never will.
"So then I’m watching it as a supporter, not as someone wishing I was there - I made the decision. I’m going, let’s have a crack. What’s wrong with that? Let’s go down swinging 3-2 rather than losing 1-0 or drawing.
"From that point of view it wasn’t great and I didn’t expect it to be."
Now into his second season with J-League side Yokohama F.Marinos, Postecoglou's men have struggled of late in the final third - failing to score in their past three matches in all competitions.
They did however start their league campaign with a bang after beating Gamba Osaka 3-2.