Brattan, at 34 years of age, became the Socceroos' oldest debutant when he was handed a start in last month's 1-1 draw with Japan in Saitama.
But the high of that moment has since been replaced with the disappointment of missing selection for upcoming World Cup qualifiers against Saudi Arabia and Bahrain.
Brattan says he understands the decision made by Socceroos coach Tony Popovic.
"Look, I'm my own harshest critic. I don't think I've been good enough the last couple of weeks. I haven't played my best football," Brattan said.
"There's no handouts, you've got to earn your spot there.
"The boys that have been called up have been in great form. I know myself I need to be better and perform better.
"I want to get back in there and play a lot more, and it starts on the weekend."
Brattan will be back in action on Sunday when his new club Macarthur take on Sydney FC.
The star midfielder spent four years at the Sky Blues and captained the club before leaving at the end of last season.
"It's strange walking in and seeing these guys," Brattan said on Friday during his joint press conference with current Sydney captain Rhyan Grant.
"Some of my best friends and people that I'll keep in contact with for the rest of my life are at this club.
"It's going to be emotional, and I'll just focus on the job at hand and get the three points."
Brattan is looking forward to his battle with Grant.
"We've had some great battles over the last 15 years on the pitch, so I'm sure there''s going to be a few words," Brattan said.
"But I've calmed down a little bit in my old age. The kids have settled me down a little bit, so I'm not as chirpy as I used to be.
"But it's going to be a great battle. It's going to be strange going up against former teammates and great friends off the pitch."
Since opening the season with a 6-1 thumping of Perth Glory, Macarthur have slumped to 2-1 losses to Newcastle and Melbourne Victory.
Sydney have two wins and a loss from three games, including last week's 3-2 victory over Brisbane Roar.
