"We struggled to carry the ball there," he said.
"We battled away, but we didn't really make a lot of metres - and it wasn't a game for making a lot of metres, the ball was too slippery.
"So we need to give those guys another opportunity next week to really see if they can step up."
Skipper Stephen Moore praised his side's reinforcements for their effort in clawing back from 13-0, but said it wasn't their responsibility to prop up the Brumbies.
"It's not up to guys who come in for their first game to win us a match - it's up to the rest of us who've been there and played," he said.
"That's disappointing that the rest of us weren't able to step up there."
Larkham was hopeful the likes of Mogg, Kuridrani, White and Dargaville would be fit for Friday's match against the Highlanders at home.
Pending the result of concussion tests, Lausil Taliauli should also be available for selection.
"We'll know a little bit more on Tuesday," he said.
Despite having lost three of their past four matches, The Brumbies remain atop the Australian conference ladder.
But the NSW Waratahs are hot on their heels after beating Hurricanes in Wellington on Saturday.
- AAP