The home side were guilty of throwing away three of their four wickets on Thursday, as they went to stumps at 4-140 in their second innings with a lead of just 40.
Aiden Markram drove Mitchell Starc straight to mid-off in the third over, David Bedingham was out hooking and captain Temba Bavuma was bowled playing across the line late in the day.
The run of dismissals came after coach Shukri Conrad admitted he was "pulling the last strands of his hair out" with his batters' decision-making in the first Test loss.
But spinner Simon Harmer said it was easy for media and fans to criticise players players without being in that situation themselves, when asked about the "questionable strokes".
"Pressure is a funny thing and I think sometimes it is easy to sit on the balcony or in the stands and pass judgement on somebody's innings or how they get out," Harmer responded.
"But there's a lot going through your head when you're waiting to face a bowler and sometimes you make the incorrect decision at the wrong moment.
"I'm pretty sure the players that feel those shots weren't good enough will be the first people to put their hands up."
Bedingham's dismissal came after he was one of three Proteas out hooking in the first innings, falling straight into a short-ball trap from Australia's bowlers.
Bavuma's wicket was also particularly poor, after South Africa's captain had done the hard work to steady the innings from 2-31 early.
But with Nathan Lyon getting significant purchase out of the rough, Bavuma tried to take the spinner on across the line and was bowled between bat and pad with five minutes left in the day.
"Look, everybody wanted us to get to the end of play three wickets down," Harmer said.
"And I don't think anybody is going to be as shattered as Temba for getting out.
"But again, it's the situation. You don't want to go back into your shell right at the end of the day. You've played a certain way. And that's cricket. It happens."
"We've got two very capable batters at the crease and still a lot of batting to come. So there are going to be casualties along the way."