Tyre struggles late in Saturday's PIRTEK Perth SuperSprint race meant IRWIN Racing's Mark Winterbottom left with "absolutely nothing to show" for the weekend.
Winterbottom qualified 21st for Friday's opener and finished 18th after tangling with fellow Triple Eight customer Todd Hazelwood on lap two.
From 15th on the grid on Saturday evening, he made his way up to eighth, only to then fall back to 15th in the final 10 laps.
"A really, really tough weekend," Winterbottom said.
"[We] struggled for qualifying speed but our race pace was actually quite solid.
"The [Saturday] night race was actually going really good and the car was really quick.
"We went from 15th to eighth, hassling [Anton] De Pasquale for seventh, and it looks like we've had a tyre failure and broken a cord or had some sort of dramas.
"Unfortunately, 10 laps to go we fell off the cliff and ended up P15.
"Tough weekend, good signs but unfortunately we have absolutely nothing to show for it."
A breakout weekend at Symmons Plains last month, which included a maiden ARMOR ALL Pole for Charlie Schwerkolt's team, left Winterbottom seventh in the standings.
Across the subsequent Phillip Island and Barbagallo events, though, he has recorded finishes of 21st, 17th, 18th and 15th, having also qualified no higher than 15th.
That leaves the 2015 champion 11th in the points, and keen to bounce back next time out at the Truck Assist Winton SuperSprint.
"[It's] tough for the guys, tough for me, we've had two rounds in a row that have been hard," he said.
"We'll bounce back, we're in this program for the long haul, we had a good start but we need a good round next one at Winton to turn our season around.
"It's hard work but we've got the crew to do it and we will fight back."