The number of Socceroos in major top flight European leagues is significantly down on previous seasons, with just two in the Premier League.
Mooy joined national teammate Mat Ryan at Brighton & Hove Albion this week, signing on loan before a $A24.85 million move is cemented in one year's time.
Luongo ended a four-year tenure at Queens Park Rangers by joining fellow second-tier club Sheffield Wednesday for a cut-price $A1.9 million.
Other Australians could find themselves in new club pastures with several European leagues still open for transfers and free agents.
That includes free agent Mile Jedinak, scarcely-seen striker Tomi Juric and now Trent Sainsbury, who has been made surplus to requirements at PSV Eindhoven.
PSV boss Mark van Bommel, the same man who held an assistant role with the Socceroos during their 2018 World Cup campaign, announced Sainsbury was free to find a new club on the weekend.
Sainsbury made just four starts last term, though he did play in the opening game of PSV's league campaign last week.
It remains to be seen where the 27-year-old could end up.
Much interest lies in Jedinak's future.
He left Aston Villa at the end of his contract in June, having helped them secure promotion back to the Premier League.
Other Australians have made club switches in the past month, including captain Mark Milligan, now at Southend United in England's League One, and Alex Gersbach, who moved to Danish club AGF.
That the Socceroos skipper is playing in the third tier in England demonstrates Australian football's low ebb.
Indeed, the number of Australian men set to play in Europe's biggest leagues this season is miserly.
Four years ago, Australia had 10 senior representatives in the top flights of powerhouse nations England, Spain, Italy and Germany.
This year it will be just four: Mooy, Ryan, and Germany-based pair Mathew Leckie (Hertha Berlin) and Brandon Borrello (Freiburg).
That figure doesn't tell the whole story as it's arguably better for players to be competing more regularly at a lower level than stuck on the bench or in the reserves.
But with less than a month before the Socceroos begin their qualifying push for the 2022 World Cup, it's something coach Graham Arnold can hardly be pleased with.
At least two Socceroos mainstays have begun their English seasons with a bang.
Ryan kept a clean sheet in Brighton's opening weekend 3-0 thrashing of Watford while Jackson Irvine scored in Hull City's 2-1 Championship win over Reading.