Western Force coach Michael Foley lamented his side's poor execution and unforced errors in Saturday's 41-7 defeat to the Brumbies.
The result was a disappointing one for the visitors after solid performances against the Crusaders and Hurricanes in the past fortnight.
The Force allowed the Brumbies to gallop out to a 29-0 half-time lead and, while the second term proved a more balance contest, Foley said his side could not afford to provide opposition sides with that number of opportunities moving forward.
"Playing against one of the top sides, we knew we had to execute early and we didn't do that," he said.
"There were some unforced errors and the Brumbies were good enough with their line speed and defence - which we knew were going to be strong - to create some more for us.
"The Brumbies played very well but there were some times out there that we made errors that cost us."
Th former Waratahs coach said putting together back-to-back performances is a key challenge in the development of his new young side.
"Every game we're chasing that little bit of consistency in our performance," he said.
"We've got a lot of young guys that are hitting highs some weeks but not necessarily able to back that up; but over time you develop that consistency and certainly playing the derby games mean a lot to us and that's why we're so disappointed tonight."
The Western Force will return to Perth to face the Reds at nib Stadium on Saturday.