Australia made just 198 and 284 in the first Test in Darwin to lose by nine wickets.
Their 210 in the first innings at Mackay, albeit in difficult batting conditions, was the fourth-lowest in Test history by a side that won by an innings.
Allrounder Cameron Green made 104 in Darwin and 67 in Mackay to be the standout batter of the series and Steve Smith was consistent with knocks of 71, 44 and 42.
Outside of that the batting returns were meagre. Labuschagne at No.3 made just 36 runs in three digs and his dismissals were all soft. He has not scored a century in his last 43 Test innings while averaging 24.69.
Cummins said a lack of runs had become a trend and the Australia captain is seeking improvement in the three-Test series in South Africa in October where Kagiso Rabada, Marco Jansen and the rest of the pace attack will be a stiff proposition.
Australia had few answers when Bangladesh paceman Shoriful Islam got on a roll in Mackay to take 7-48. Cummins said it was a question of how to "weather the storm" in those situations.
"If we want to stay number one in the world and win every Test match and be as good as we think we can be, I think we were probably a little bit below par in both Test matches," Cummins said after the second Test win.
"There were a couple of shining lights. Greeny had an awesome series and every time he batted he looked really solid.
"We probably could have extended that lead yesterday and taken that game away from them and put on a 250-plus lead. That goes for me as well. I am part of the batting group."
Cummins said it was time to reconsider the approach the batting unit took to their task and play to the conditions.
"I think you have to. When you are not scoring your runs you have to look at your style and your method," he said.
"Take last week. I thought Bangladesh played to their tempo and slow-played a little bit (while scoring 426 in Darwin).
"We could have perhaps been a little bit more patient so I don't think it is always about hitting your way out of trouble.
"When the conditions get a little bit extreme we don't want batters who are sitting ducks.
"You've got to find a way to turn over the strike and make your margin of error a bit smaller and make the bowler think about being more worried about missing the spot."
Cummins was asked if he could guarantee Labuschagne would be part of the side for South Africa.
His answer was far from an endorsement.
"I don't reckon I can guarantee anyone really. He's not scored the runs he would've liked," Cummins said.
"I did say a couple of days ago – and I think it still stands – he's been batting fantastically well off the field. But it doesn't mean much. You've got to convert that into runs out there.
"We've got a bit of time. Selectors will get together I'm sure in the next week or two and start nutting out that next Test squad.
"We know he's class when he's at his best, and going into this series we thought he was pretty close to his best.
"But he needs to start transferring that into runs out there, so we'll see in the next couple of weeks."
