The Chinese Super League has been on hiatus since August in order to aid China's own bid for qualification but, with a resumption looming, the 31-year-old has been called back to Shanghai Port FC.
"His Chinese club made him come back to China because he hadn't been in China for a couple of months," Socceroos coach Graham Arnold explained to reporters during a press conference.
"The Chinese government's rules and regulations are that he had to do 14 days quarantine, and then after 14 days quarantine it's 14 days self-isolation, which took days into our camp.
"Unfortunately for Aaron, he's out of this camp. I've had conversations with Aaron. He's devastated he can't be here because of the contractual situation in China with the salary he's getting paid has made him go back."
How this was said, and what wasn't being said, spoke volumes. Arnold's clear dismay at Mooy's unavailability during that press conference -- along with lament over the truncated time the Socceroos coach has at international level -- hinted that the midfielder's place is secure once he is available.
In Australian circles, Mooy's injury-forced absence from the 2019 Asian Cup was cited as an important factor in the Socceroos' quarterfinal exit to the United Arab Emirates.
However, Australian football has really never sought to examine how Mooy impacts the game. Consequently, one must ask how important he actually is to the Socceroos and should his spot be so secure, irrespective of age and relative lack of club minutes?
At the best of times, Mooy's pinpoint accuracy in distribution would come at a trade-off, but that trade-off was arguably never in relation to a widely perceived defensive fallibility. That passing range of his was rarely ever weighed up against the risk he never seemed to embrace both in and out of possession, while Australia had the ball.
And against Asian opposition, the Socceroos have a lot of the ball. In this World Cup qualification cycle alone, Australia hold the highest average time in possession at 34:57 (per Instat), nearly three minutes more than the next best in South Korea at 32:24.
Yet, Arnold's side ranks fifth out of the 12 teams for xG per 90 (1.51) in this third phase of AFC qualifying, and equal fourth for xG per shot (0.12). When looking at why Australian possession has been so laboured in recent past, Mooy tends to be a microcosm of this issue. Starting as a left-sided midfielder in Australia's 2-1 loss to Japan in Saitama last October was the latest such example.
Even on the most basic of logical levels, a creative midfielder who doesn't like looking for the ball in tight areas seems counterproductive. This is before considering what Arnold's deployment of Mooy in that game meant -- putting that creative midfielder in a position where they specifically have to go looking for the ball in tight areas.
As a result of that allergy to risk in movement and consequent inability to collapse the Japanese defence, the two players who received the most passes from Mooy that night were Aziz Behich and Harry Souttar -- Australia's left-back and left-sided centre-back.
There was one particular moment that highlighted this early, and it was not even with the Japanese defence set. It was in transition. In the 10th minute, with Australia already 1-0 down and in need of an immediate response, Taggart breaks clear on the left. Needing to provide support, Mooy hesitates, because it means he has to receive the ball in a way that tests his first touch.
Japanese defender Hiroki Sakai is then able to recover. What was a two-on-two situation becomes a two-on-three. The move slows down. The threat evaporates.
According to Arnold, however, Mooy's particular deployment that night was a case of needs must.
"Aaron always brings the luxury of playing different roles -- as a defensive midfielder, he did that against Vietnam well, he did that against China and controlled the game for us, to play out the game.
"Against Japan we put him higher up the field, where he's very, very happy to play. I felt he did some good things."
In reality, this qualification phase has highlighted Mooy will only provide an amplification of that traditional trade-off. In addition, his distribution is arguably becoming just as risk-averse as everything else in his game.
On a primary level, Mooy's passing volume in relation to collective end product and dribble volume contradicts the belief he can capably fill different roles.
In addition, whether the 31-year-old would fit next to a specifically defensive presence at the base of midfield is even more questionable at this point. This is particularly relevant considering Arnold has traditionally been a coach so firmly adherent to his system.
International football can admittedly fall prey to sample size. An accurate profile of Mooy the footballer can still be gleaned from some of his per 90 averages, compared to other midfielders in this AFC qualifying cycle -- a lot of passing, a lot of ball recovery, sporadically evasive dribbling, questionable impact on the collective.
His status in the Socceroos setup ultimately looms as something that could define their World Cup qualifying campaign.