The 38-Test Frost was one of the big-name omissions for the Australians ahead of their Nations Championship Tests this month after missing just two games of the Wallabies' last 15 Tests before the series.
The towering second-rower wasn't part of a chunk of the ACT Brumbies' Super Rugby Pacific season as he battled with a knee injury that left him unable to stand or sit comfortably.
But despite returning for the club in round five, he didn't do enough to impress selectors.
"They were pretty honest with their feedback and I was honest when I was up there as well with how the season panned out and how I was feeling at the time," Frost said on Thursday.
"(I needed to) get back to playing my rugby again. I didn't feel like I was at (my level) this year.
"I was realistic with how I had been playing, and then in general how the other boys have been playing, and how much they have had great seasons."
Frost wasn't the only back-rower to face the axe from coach Joe Schmidt, with Queensland Reds lock Lukhan Salakaia-Loto also dropped while rookies Lachlan Shaw and Miles Amatosero were called up instead.
But with the Wallabies now on a dismal six-game losing streak going into their clash against Italy on Saturday, Frost has left the door ajar for a return.
After the Nations Championship, the Wallabies will face Eddie Jones' Japan on August 8 in Les Kiss's first game as head coach.
Although Frost has one eye on returning to the squad ahead of next year's home World Cup, he's happy to keep rebuilding in Canberra's club rugby competition.
"This block has been really cool. It's been a fun time for me because I haven't really had an experience where I have time to train and really go hard in the gym to get fitter, faster, stronger," Frost said.
Elsewhere in the Brumbies camp, ACT have boosted their outside back stocks by signing NSW Waratahs product Triston Reilly on a two-year deal.
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