World-class halfback Will Genia was benched, another Queensland protege, James Horwill, was stripped of the captaincy and wayward star James O'Connor was shown the door.
The surprise elevation of test rookie Ben Mowen to the captaincy and a reformed Quade Cooper to the vice-captaincy has been inspired.
McKenzie admitted the response to his hard calls will ultimately determine their outcome.
"It's not about trying to please all the people," he said. "I learned long ago you have to make the right call for the right reasons.
"It's not a popularity contest."
Mowen and Cooper were among the star performers on the five-test European tour which could have reaped a grand slam of the four Home Unions if not for a couple of controversial refereeing calls and an inability to cope with the second-half pressure in the 20-13 loss to England.
The continued rise of code-hopping fullback Israel Folau, who has become one of the most potent attacking players in the game, and energetic flanker Michael Hooper have also immeasurably renewed hope.
McKenzie and scrum guru Andrew Blades' work with the pack, led supremely by hooker Stephen Moore, has also changed worldwide and refereeing perceptions of their "Achilles' heel", the scrum.
The pain of the first nine months of the year - where they lost the Lions series 2-1 and were then whitewashed by New Zealand and South Africa - remains, but it's now proving more of a motivation.
"We've obviously had a lot of ups and downs this year but from where we were to where we are has been a really important step," said Mowen, who won just one of his first six tests from his debut this season.
"Upon reflection, there will be happiness in the way we are going.
"[But] you want to make sure you don't move on too easy from those periods and they don't sit well so the next opportunity you get you're really hungry."
Cooper, who described the Wallabies' culture as toxic last year, felt the end-of-season tour had made them into a "bigger and better team".
"We've made a lot of things [happen] that we didn't think were possible as a team in terms of culture," the five-eighth said.
"We want to be the best in the world, we're not hiding that, but we know that that path is a long and a tough path."
- AAP