Rugby Australia boss blasts predictable Super Rugby
"We need teams that are performing consistently and that any team – be that South African, New Zealand or Australian – has the capability to win," Castle, a New Zealander, told Fox Sports late Wednesday.
All-conquering New Zealand sides dominate Super Rugby with Australia's teams losing all six encounters against them this season, continuing a miserable run stretching back to 2016 that has seen Aussie sides lose the last 38 trans-Tasman matches.
The axing of the Western Force this season, reducing Australian teams to four from five, was supposed to improve the strength and depth Down Under. But little has changed.
"What we've seen this year is some better TV audiences, we've seen some better performances, but we haven't beaten a New Zealand team [and] that's still the thing that everyone is looking for," Castle said.
Super Rugby restructured this year, slimming down to 15 teams in three conferences from 18 in four, in a bid to keep the competition relevant.
It followed a strategy paper by governing body SANZAAR saying the previous format was "confusing, lacked integrity and was ultimately not supported by fans, stakeholders and commercial partners".
But even with 15 teams, there is apparent discord with Australian media reporting this week that disillusioned South African teams could leave once the current broadcast agreement expires in 2020 to play in Europe.
SANZAAR denied this, insisting all member unions were still on board and involved in an ongoing review to determine Super Rugby's future up to 2030.
Castle said the most important thing was to produce a competition that "has uncertainty of outcome".
"We certainly haven't had that over the last couple of years with the New Zealand team performances and that's what [does not] involve crowds, doesn't sell tickets, doesn't have people watching on the television.
"The hope that when you buy a ticket and sit down you believe your team can win – that's the competition model that hugely important and what we're striving for."
She said the structure of such a competition was what rugby authorities were working on, amid reports that a push into North America was being considered.