Former Test opener Matthew Hayden has called for Matt Renshaw and Sam Konstas to be recalled after No.3 Labuschagne and opener Jake Weatherald continued their lean run in the shock nine-wicket loss inside four days in the first Test in Darwin.
Allrounder Beau Webster made just 12 and five and his defensive technique was also found wanting.
McDonald said the calls for change were inevitable and understandable.
"A lot of people call for change even when we are winning. They are entitled to do that too on the back of a performance like that," he said.
"Why wouldn't they? That is part of our lot. Lose a game and there are going to be calls for guys (to be dropped) who aren't performing to the levels they would like or we would like."
McDonald was asked if there was scope to add to the 13-man squad officially named for the two Tests, which also includes spare batter Josh Inglis and paceman Scott Boland.
"We could add to that. It is a very light squad that we have," he said.
"We will make those decisions in the coming days as to ... potentially adding or sticking with what we have got."
McDonald said his side's match tally short of 500 runs in Darwin was unacceptable on a good surface. Australia made 198 and 284.
"I think we are better than that. I can't sit there and defend that," he said.
While McDonald admitted batting wasn't the only issue, the microscope is on Labuschagne and Weatherald ahead of the second Test from Saturday in Mackay.
Both have made changes to their technique to try to regain form. Weatherald averages 20 in six Tests and Labuschagne is searching for his first century in the format since 2023.
Labuschagne scored one in the first innings in Darwin and was looking good on 31 in the second dig until he missed a straight delivery.
"He is disappointed at that, a missed opportunity. He needs some big runs," the coach said.
McDonald said some of the changes the No.3 had made held up well under pressure, but with a caveat.
"It was 31 he got in the second innings and up until the point he got out you could sit there and say, 'Geez he was looking good. He's moving well and clipping off his pads and (hitting) down the ground'," he said.
"It is easy for me to sit here and try and defend that but ultimately it is 31. It is not a big score.
"He has lacked runs. He feels that. We feel that. We are working incredibly hard as a coaching group. We have got to get the best out of Marn as well."
Weatherald's 23 and 0 were not what he was after, flashing at a wide one then chopping on in the second innings.
"There was some change to Jake in terms of where he lined up and his movement patterns," McDonald said.
"It is probably harder with that smaller sample say to say, 'Yep that is going to hold up under pressure'."
Small sample sizes are not what Australia want from their top order in Mackay.
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