Daly Cherry-Evans believes the introduction of high performance standards and player welfare measures at international level has helped close the gap between Australia and other nations.
The IRL, in consultation with the RLPA and NRL, has introduced minimum requirements for nations to ensure players are exposed to a similar environment in Tests to those at their clubs.
Tonga’s 16-12 win at Eden Park on Saturday night was the first time a tier-two nation had beaten Australia, who did not lose a Test series or tournament from 1978 and 2005 and are the current World Cup holders.
However, Cherry-Evans believes the international landscape has now changed as tier-two nations are benefiting from the improved conditions.
"We are facing countries now where the professionalism is through the roof and there are minimum standards around the game," the Kangaroos vice-captain said.
"The second-tier nations are at the minimum standard, where they have the support of the coaching staff, the medical staff and the playing group have those things around them to make them a top-tier nation.
"I think Tonga is the perfect example of that, where given the opportunity to play the right sides and the coaching staff they are there to take advantage of you now."
Match Highlights: Tonga Invitational v Australia
Tonga are coached by Kristian Woolf, who will fly to England on Tuesday to take charge of Super League champions St Helens, while Cowboys assistant David Tangata-Toa has been joined on the staff by former Brisbane and Penrith mentor Anthony Griffin and Dragons assistant Dean Young.
All other members of Tonga's off-field staff are also involved with NRL clubs and Kangaroos coach Mal Meninga acknowledged Woolf’s influence in his post-match address to the players.
"As an Australian side you want to win every game," Cherry-Evans said.
"It is the No.1 sport in Australia so we understand what comes with wearing the jersey.
"Mal was pretty clear that we didn’t meet those standards in the second half and he also made it very clear that Tonga is a very good nation, a very good side, well coached with a lot of star power so if you give them opportunities they are going to take them."
Asked where he now rated Tonga, Cherry-Evans said: "They are obviously up there, they just beat us. I know the World Cup is a long way away but if they continue to grow as they have they are going to definitely be one of the teams to beat."