"Opportunities for people who love the game, because those figures are undoubted, more people love the game, play the game than ever before, boys and girls.
"Having more teams, that was probably the biggest strength of the National Soccer League, there was 14, 16 teams and the majority of the golden generation came from there because they had an opportunity to realise those dreams.
"When you don't provide opportunities, they don't only stop playing but walk away from the sport in many respects - they don't follow a team.
"I understand there's economics behind it but from where I sit, there's a real need for it, sooner rather than later.
"As I said in the book, I'm pretty bullish about it, it needs to happen. I'm not an administrator, but it's worked for us in the past."
In the book, Postecoglou questioned why the success of the Western Sydney Wanderers "didn't fire up the game to be bolder" and to break the 'consolidation and sustainability' mindset.
Postecoglou said a second division should be a longer-term play, but cited the FFA Cup as an example of what opportunities have done for non-A-League clubs.
"For me the first stage is getting more teams in the top division, provide more opportunities for players and supporters and from there, growth will happen. What form or shape, time will tell," he said.
"The FFA Cup has shown that little opportunity to just be in the spotlight is a massive incentive and it's been embraced by the whole football community.
"I went to Bentleigh Greens (against Melbourne Victory) and they spent $50,000 on new lights, which are there to stay, they've built something tangible, I don't think they would've done that before.
"You've improved a club by giving them opportunity and that can happen everywhere across the country if there's incentive.
"It doesn't necessarily mean you'll get to the top league in the next few years, but it gives them incentive to keep building."
