When the frustrations of several key decisions from Saturday night's heartbreaking loss to Wales subside, the Wallabies can take pride in the fact that this was their best performance of the tour -- but there should be little confusion as to where the improvements must come in 2022.
The 29-27 defeat by the Welsh will sting, not just for the fashion in which it came about but also the fact that it made it three straight losses to finish the year. From a 7-4 record pre-tour, the Wallabies sign off 2021 at seven apiece, further chastened by the knowledge that they were in a position to win all three of their U.K. assignments.
But having lost a third straight penalty count in the United Kingdom and been served with a further two cards -- one of each shade -- in Cardiff, it is abundantly clear where the Wallabies need to right their game if they are to continue their upward trajectory of this year - albeit one that has plateaued this November.
"We're incredibly proud of the effort, that was massive," Rennie said after the loss to Wales. "We said that we were going to empty out the tank for each other and when you're one short and two short, you've got to do that.
"So heaps of character, we got put under the blowtorch and I thought the boys responded really well. I'm really proud of the guys but as I said I thought they deserved better."
Rennie is right to rap his side's character and courage. Playing a man down for 65 minutes and then as a virtual rugby league outfit for 10 of those, logic suggests that Wales should have won this game and won it comfortably.
But just as they had done against France in the third Test in Brisbane in July, when Marika Koroibete had been sent off after only five minutes, the Wallabies played some excellent rugby, scoring three superb tries to put a temporary injunction on the idea that they can't play without Samu Kerevi.
Australia are undoubtedly a better outfit with the Suntory Sungoliath centre in their midfield, but such were the performances of Hunter Paisami and Len Ikitau in Wales, and the fact they are both only 23 years of age, that it's fair to say Rennie has a centre combination to build on if Kerevi is not available.
Just where that conversation lands, the Giteau Law to be precise, continues to be the source of great discussion across Australian rugby and one Rennie plans to present his own take on to the Rugby Australia board before Christmas.
While many thought Kurtley Beale's time in the Wallabies jersey had been and gone, on the strength of his efforts against Wales such talk may be a tad premature. The veteran Australian back is now only five Tests short of a century of Wallabies caps; given the journey of his career, it will be a mighty achievement if Beale is able to reach the ton at some point over the next two years.
As good as it was to see Beale beating opposition defenders on the outside and finding space through a fractured kick-chase through the middle of the park, the sight of Will Skelton carrying into the line with impetus and then winning what looked like being a match-winning penalty was just as welcomed.
At last, Skelton was given enough time to impart his massive frame on a contest when the Wallabies were actually playing with some continuity, which wasn't the case against either Scotland and England. Rory Arnold, meanwhile, again delivered what we have come to expect from the former Brumbies lock, an unerring work-rate on the carry and in defence and as well as being an assured lineout target.
The uncertainty at hooker across the board within the Wallabies means Tolu Latu will also continue to hear his name mentioned in discussions, pending the outcome of the Giteau Law review. The impact a hard-running Taniela Tupou can also have on this Australian team was also evident in Cardiff, while Rob Leota has emerged as one of the finds of the season.
But it was a shame that probably the Wallabies best forward of 2021, outside of skipper Michael Hooper, got his tackle technique wrong in Cardiff. There is not a bad bone in Rob Valetini's body and the softly spoken Brumbies back-rower was the first to admit that he had simply got his tackle on Adam Beard wrong.
Where Koroibete's red had been ruled incorrectly earlier this year -- the first point of contact on that occasion being the shoulder before the officials were fooled by the whiplash generated by the impact of the hit -- Valetini paid the price for not dropping his bodyheight despite the contact being head-on-head.
"I don't have an issue with the red card because that's the way it's been refereed these days; Rob's responsibility is to drop his height in the tackle and he didn't," Rennie assessed. "And he had a head clash, so you've got to take that on the chin."
What Rennie did however have an issue with was the yellow card given to Kurtley Beale for a deliberate knockdown, while later in the second half Wales centre Nick Tompkins seemed to commit a near identical play but instead earned his side seven points.
Rival supporters will argue with one another until they are blue in the face as to what the right call was for both incidents, but the cold hard truth is that the deliberate knock-down law has been a mess for years, and one only further muddied by the endless slow-motion replays and interruptions of the TMO.
Tompkins action was arguably more deliberate than Beale's ever was but purely for the fact of his sweeping motion which just managed to propel the ball backwards, or at least straight down, referee Mike Adamson and TMO Marius Jonker stuck with the decision of try. Still, how a ball knocked down in front of a player towards the opposition goal-line can be adjudged to have traveled backwards is dubious at best.
That there is little more than one centimetre between seven points for one team and a 10-minute spell down a player for another perhaps says it all about rugby's law book, or at least the deliberate knock-down law itself.
"I wasn't happy with Kurtley's yellow card, he's making an effort to wrap two arms and it clips his hand on the way through and they find a yellow card for that," Rennie queried of the Beale incident.
"And yet [Tomkins] slaps the ball down in open play, somehow that say it didn't go forward when he's facing forward, and they get seven points out of that instead of getting a yellow card and us getting a penalty.
"There were lots of decisions today which I'm not going to go into that had a massive bearing on the game. Our boys played with a lot of courage and a lot of heart tonight, and we almost did enough to win that."
Despite the results of the last few weeks, there is no question that Rennie has this Wallabies group in far better shape than the team that stumbled and bumbled its way through the hastily arranged 2020 Test calendar. They may have not completely consolidated their progress from the Rugby Championship, but Saturday night's performance was far closer to those four victories than their efforts of the past two weeks.
A number of new players have been introduced and shown they belong at Test level, there is increasing depth across a number of positions, and the squad is united in the positive manner it wishes to be perceived.
Sure, some off-field decisions disrupted this tour and there is clearly a big one to come regarding exactly what shape the Giteau Law takes moving forward, but the quiet optimist would look to 2022 with a degree of excitement.
Once the frustration of Saturday night dies down, the Wallabies should take on a similar quiet optimism, too.
Drawing a line in the sand on their discipline, further refining their tackle technique and developing their rugby smarts, will determine whether Australia takes another step forward in 2022.
They will need to do so, too, with England headed Down Under in July. Eddie Jones' side may have endured a poor Six Nations but armed with the injection of some fresh blood this November, they will prove formidable foes for the Wallabies once again.