The centre half came out and criticised the club’s recruitment in recent seasons.
Romero felt the team had not been strengthened to the necessary level in the summer window.
Postecoglou told reporters: “In the context of the day, Cristian was really disappointed obviously. More than disappointed in that he'd worked hard to get back, it was a big game for obviously, he knew that, and he had to go off and then watch the team have to feel the pain of another defeat in the manner it happened. He was obviously very emotional.
“He's a leader in the club, he hasn't been able to help us, I think it was his way of trying to as a leader help us in the group. We're going through a tough time and he believes in what we're doing. And then the other part of it probably he went about it the wrong way.
“He's passionate about having success at the club and the way he expressed it was not the right way in a public sense. I don't feel and it's certainly not my belief that our challenges at the moment are down to one thing or one person, I don't believe that, I never have believed that.
“Whatever we need to do, we have the power to do that but it'll only happen if we stay united as a group particularly through difficult times, get through to the other side. I fully believe if you can do that, you come out stronger.
“Cristian realises what he said...a lot of what he said was good, some wasn't right and shouldn't have been done in public. We deal with these things in our own four walls. There's always issues we need to deal with. The same way I wouldn't criticise a player or anyone else, we shouldn't be doing that in a public sense.”
On possible repercussions, he added: “I just think you deal with these things internally. I just don't think there's any benefit for us. I know people get really salacious about punishments and stuff. They really love that sort of thing. I think I'm pretty consistent in saying I don't just think that's important. I think what's more important is an understanding of how we should deal with these things and deal with them better.
“I’ve already spoken to Cristian about it and and you know, he's apologised for the fact that the way he said it, particularly in the public sense, wasn't the right way to go about things. He's a human being, he got emotional and I think he just expressed what he wanted to express, probably in the wrong way.
“He does care. I think it would have been easy for him not to say anything. He does care, but there's a way to do these things and a way to express yourself and the way he did it wasn't the right way.”
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