Despite dominating sections of the game, the Brumbies lost 17-28 to the Bulls in South Africa and in doing so lost any chance of making it through to this year's semi-finals.
Mortlock said that his team lacks experience, especially at some of the most important positions on the ground.
"It's a bit of a reflection of where we're at as a team," Mortlock said.
"We've got a lot of young guys, particularly our decision makers - our nine, 10 and 12. Our combinations are still very fresh and that takes time to steer a team around, particularly under these new ELV's (Experimental Law Variations).
"You've got to be very quick and sharp to make decisions as you see the opportunities arise."
The loss capped off an unsuccessful South African tour for the Brumbies which saw the Canberra-based side lose to the Stormers and Bulls by double figure margins.
Mortlock said his team had played some good rugby during the past two matches, but had nothing to show for their strong efforts against quality opposition.
"From our perspective - as a team - we're creating a lot of opportunities in attack, it's more a case of being able to capitalise on that and that takes time," Mortlock added.
"I think ELV's or no ELV's, we're a bit frustrated at where we're at but as a team we can learn from this experience.
"Over the last two weeks we've played a lot of positive football and have got no pay for it… which is disappointing."
The Brumbies will travel to Western Australia for the final game of the season to tackle the Western Force on Friday night.
Both teams will have pride to play for after the Force were knocked out of the semi-finals race on Friday night when they lost 21-10 to the Hurricanes.