Coach Dave Rennie lamented Australia wasting too many chances after throwing away a hard-fought series to a resurgent England and said the Wallabies will "have to be better" as they start preparations Sunday for next month's Rugby Championship.
The home team were bursting with confidence after clinching the first Test in Perth 30-28 to end an eight-game losing streak to England since the 2015 World Cup.
But a 25-17 defeat at Brisbane followed by Saturday's 21-17 defeat in Sydney, where they led 10-3 in the first half, mean they have lost five of their last six Tests as they head into matches against Argentina, South Africa and New Zealand.
Most of those defeats followed a similar script, with the Wallabies creating opportunities but failing to finish.
A slew of injuries forced Rennie to shuffle his side, but he has often pointed to the depth of Australian rugby and would not use it as an excuse.
"We had plenty of chances so it hurts ... We created a lot of opportunities and had the right plans but we just weren't clinical enough," he said after the bitter defeat at the Sydney Cricket Ground.
"It's disappointing because at this level, you have to take your chances and we left a lot out there.
"We have to be better. We've got a lot of footy (left), we're three weeks into a season so we have a few things we need to tidy up heading into Argentina."
Australia started aggressively in Sydney with Tom Wright's try putting them 10-3 in front, but a series of blunders allowed England to score 18 unanswered points and take control.
Michael Hooper, the Australia captain, said the defeat "really hurts" after they threw everything at England in the final stages.
"We grinded and played some good footy. There's so much grit in this group. There's a lot of adversity, but no excuses," he said.
- 'You learn a lot' -
In contrast, England and coach Eddie Jones head home after a long season with the pressure off after facing criticism for a poor Six Nations campaign then a thumping defeat to the Barbarians.
Victory ensured they became only the second England side to win a series in Australia after a historic whitewash in 2016, also masterminded by Jones.
The affable Australian said it boded well for his young side, who showed heart and defensive courage as they build towards the World Cup in France next year
"I'm pleased for the players, we have a very young squad here and they learned about the game," he said.
"The first and third Tests were very similar. We started both those games poorly, gave Australia some points and we had to claw our way back into the game.
"First Test we didn't quite fight hard enough but this Test we fought pretty hard and particularly the young finishers did a good job for us."
Captain Courtney Lawes, preferred to lead the side ahead of Owen Farrell, was full of praise for what they had achieved.
"I think it really showed what it means for us to play for this team. We had a tough start to this match and series, but we showed what we're made of," he said.
"We did what we said we wanted to, which was improve week on week. This game was a tough battle, but you learn a lot every week -- even when you win."