Ferns co-captain Gina Crampton admitted their start was unacceptable.
"The start was what got us, we can't start like that against Australia, let alone any team, just the small errors were disappointing," she said.
"We left the fight too late. They had the lift on us, and we looked like deer in headlights at times."
In the absence of Ferns captain Ameliaranne Ekenasio, who was rested with a calf injury, Monica Falkner got the nod to join Maia Wilson in the shooting circle.
But up against the formidable Courtney Bruce, Falkner struggled to create opportunities to score and was subsequently subbed for greater experience in Bailey Mes.
Australia's dominance saw Ferns coach Dame Noeline Taurua uncharacteristically look to her bench more than once, calling on a fresh midcourt in debutant Maddy Gordon, Whitney Souness and Sam Winders.
The changes continued as Taurua reshuffled her lineup several times throughout the second quarter, but nothing seemed to work as the Diamonds continued to pile on the goals.
Ferns defenders were left scrambling to find ways of shutting down Cara Koenen, who shot comfortably at 85 per cent in just her second match for Australia, leading the Diamonds to a 14-goal lead at halftime.
After blaming "individual errors" at the break, the Ferns returned with a fresh approach and started to chip away at the advantage.
Sulu Fitzpatrick and Jane Watson settled in the defence circle, finally able to disrupt the Diamonds' flow and force much-needed turnovers for the Ferns.
But it proved a case of too little too late as Australia held tightly to their helpful buffer to claim the second test and level the series at 1-all.
It leaves the Ferns with plenty to address but they'll have more than 24 hours to do so, with the third test scheduled for Saturday.
