Postecoglou believes they are developing, showing there is talent outwith the ‘certain markets’ Scottish clubs tend to scout.
The Celtic boss has already plundered the J-League in Japan for signings and admitted he was keeping tabs in Korea, Iran and Down Under last year.
He explained: “I look everywhere, mate. I don't look at one market.
"Here, they seem to be focused on certain markets but I know talent can be found anywhere in the world, including Australia.
"Asian football is something I have knowledge of, and I am very fond of. Not just Japan, but other nations.
"In terms of Australia, I have better knowledge and good information. The lads at Hearts are doing well and it's great to see them developing.”