According to the business case prepared by KPMG, a redeveloped ANZ Stadium would not meet the requirements of the Australian Rugby League Commission agreed in a memorandum of understanding with the NSW government, which meant there will be a “decrease in both the number and frequency” of blockbuster events hosted at ANZ Stadium. For instance, KPMG assumed one in every three NRL grand finals would be sold interstate.

The NRL has since committed to playing the grand final in Sydney for the next 25 years, while a subsequent internal government review found the assumption that Sydney would lose major events if it only redeveloped ANZ was too conservative.

Nevertheless KPMG assumed that redeveloping ANZ – as the government proposes to do – would likely lead to only a 10 per cent average increase in attendance. In contrast, building a completely new stadium would likely have led to a 15 per cent increase in attendance.

The assumptions about attendance increases came despite attendance at sporting events declining in recent years.

The business case for a new Moore Park stadium also assumes an average 15 per cent increase in attendance. And it relies on an assumed increase in the number of international and domestic fixtures.

For instance, the business case assumes that a new Moore Park stadium will deliver two extra major concerts a year, two “other events” a year such as US college football, one extra international soccer fixture a year and another international rugby league fixture.

The document also assumes that, if the existing Allianz Stadium was not overhauled, NRL clubs would have played at least three fewer fixtures a year there – or only 10 a year. In contrast, building a new stadium will result in at least 16 NRL games a year played at a new Moore Park stadium, the document assumes, rising from the current 13.

Labor’s sports spokeswoman, Lynda Voltz, criticised the assumptions for under-estimating the number of games currently played at the stadium, which made the case for a new stadium look better.

“For Allianz Stadium the government appears to have taken every care presenting the best possible case to ensure the Sydney Cricket & Sports Ground Trust gets a new stadium,” Ms Voltz said.

The government’s chosen option of a refurbished ANZ Stadium does not allow for a retractable roof to be fitted. This means Sydney will remain without a major stadium with a retractable roof; the roof at Etihad Stadium in Melbourne helped that city win the rights to host the US men’s basketball team in two fixtures against the Boomers next year.

The Sports Minister, Stuart Ayres, said: "The transformation of Stadium Australia will bring 46,000 fans closer to the action, provide roof cover for every seat and keep the NRL Grand Final in Sydney for the next 25 years."