Dave Rennie thought the Wallabies made large strides during his three years in charge and believed he had the support of players and staff before his sudden axing.
The New Zealander released a statement on Wednesday, his first public comments since Eddie Jones replaced him in a shock coaching switch ahead of September's Rugby World Cup.
Rennie's contract was to expire at year's end, the coach last week adamant he would lead the side to France and that Jones - himself let go as England coach in December - would not be involved.
"I'm disappointed I won't be able to see out my contract in the way I agreed to back in 2019 but leave knowing I had the full support of the playing group and the staff," Rennie said.
"I certainly felt we have made massive shifts over the past three years both on and off the field, which is off the back of a hell of a lot of hard work put in by good people.
"I wish Eddie, the staff and the team all the best in what's a massive year, with the Rugby World Cup less than nine months away."
Rennie's win rate of 38 per cent ranks as the worst of anyone who has coached the Wallabies in more than 30 Tests and was a major reason behind Rugby Australia's brutal call.
But supporters have claimed he was harshly treated, Rennie taking the job at the height of the COVID-19 constraints and then gutted of key players due to injury.
In his last tour they beat Scotland and Wales but lost to France, Ireland and Italy by a combined five points.
Whether Rennie's coaching style had led to many of those injuries was up for debate, while the consistently poor on-field discipline of the world No.6 side was another black mark as RA chiefs tossed up his future.
They turned to Jones, who piloted Australia to the 2003 World Cup final, before impressing with Japan at the 2015 World Cup and then taking England to the 2019 decider via a semi-final defeat of New Zealand.
Jones, on a five-year deal, will start work in late January and conduct interviews with the remaining assistants before making a decision on his support staff.
One of those is Dan McKellar, who left his head coaching role at the Brumbies to assist Rennie in a partnership many viewed as a stepping stone to the top job.
"The staff I worked with during my time with the Wallabies are some of the best in the world and they played a massive role in creating a quality environment and developing the depth of the playing group," Rennie said.
The two-time Super Rugby-winning coach finished with a comeback win over Wales, their injury-hit squad finishing a dramatic tour of Europe on a high.
"The support has been immense and much appreciated from the more than 500 messages I've received from current and former players, coaches, administrators and friends both here and abroad," Rennie said.
"I've loved my time with the team. They're outstanding young men who are keen to learn and prepared to work hard.
"I'd like to particularly thank those in the Australian Rugby community for their support of the team over the past three years and for all the words of encouragement when we have crossed paths in schools, on the training field or in airports around the country."