He admits it was a major disappointment but hopes to be one of the final players added by the Wallabies on June 11.
"I spoke to Robbie on the Sunday morning (before the Wallabies squad was announced). He told me I was unsuccessful in making the 25, but to keep building my game and continue what I'm doing," said Mogg.
"As long as there are six spots open, there's always a chance to make it.
"I was disappointed in not making the 25 and if I don't make the final six, I'll be disappointed again, but I'm not going to let if affect my game. I'm not going to drop my head.
"I'll play positive rugby with the Brumbies and if that leads to a chance of making the final six, I'll be happy with that."
The 23-year-old is nicknamed Greyhound for his speed and slender physique, but Deans has pinpointed his physicality as an area of concern.
And while Mogg is ready to work on the weakness he does not believe he needs to add any extra weight.
"It's just the physicality of Test rugby he is concerned about," sais Mogg.
"I showed last year at some points in the competition I wasn't physically capable, but this year I've grown.
"It's something I'll always have to keep working on and hopefully get there sooner rather than later.
"I'm pretty happy around 90 kilos. I guess I can put a little bit more on, but at the same time speed is one of my greatest assets.
"I don't want to jeopardise my speed for a few extra kilos that I might not have to have."
Mogg endured an uncharacteristically poor game in the Brumbies' loss to the Crusaders a week before the Wallabies squad was announced.
But he regained his form in the Brumbies' loss to the Waratahs and the victory over the Blues.
"I found a bit of confidence in that (Blues) game, especially my kicking game and under the high ball," added Mogg.
"(My form) wasn't really down, but it wasn't where it has been. I had a pretty poor outing against the Crusaders, but I thought I turned it around against the Waratahs. I didn't think my kicking game was that strong against the Crusaders.
"But I found my rhythm against the Waratahs and continued that on Friday. I really wanted to put in a solid performance against the Blues.
" I guess I played my part in the way we won and how we wanted to control the game."
The Brumbies remain at the top of the Australian Super Rugby conference and remain on course for a home semi-final.
And they return to Canberra on Friday night to take on the Hurricanes.
"It will be really good to get back to Canberra Stadium," added Mogg.
"The last time we played there against the Crusaders we were a bit disappointing.
"To get back in front of our home crowd against quality opposition like the Hurricanes, who on their day can really turn it on, will be really good.
"Hopefully, we can just follow up the way we played last Friday and take that into the Hurricanes game."