A pre-Christmas outbreak of COVID-19 in Sydney led to the ACT tightening its border restrictions, meaning half a dozen Brumbies had to modify their festive plans to avoid being shut out for two weeks.

Young gun Nick Frost was in Sydney, and opted to come back to Canberra prior to Christmas before the border tightened.

Bayley Kuenzle, Billy Pollard, Luke Reimer, Lachie Albert and new boy James Tucker were all set to visit Sydney for the break but stayed behind to avoid a fortnight in quarantine on their return.

It proved the final sting in the tail of a rollercoaster 2020 for the Super Rugby AU champion Brumbies, who also endured bushfires and a mumps outbreak amidst the global coronavirus chaos.

"[It was] tough on the players, tough on the parents and the brothers and sisters as well," McKellar said.

"I'm sure there was some emotion involved for a lot of the players there and their family. It's another great example of how our players just adapt and get on with it.

"They understood it was the circumstances, the world we live in currently. They understood that it was for the team and for them individually to avoid two weeks of quarantine, and to live life as normally as we can here in Canberra.

"The preference certainly would've been to be able to have their break as planned with their families.

"We're pretty fortunate here compared to some parts of the country. It was something that they just had to do in the end."

It means McKellar has a full complement of players at preseason training, barring the Brumbies' Wallabies stars who aren't due back at the club until the end of next week.

Super Rugby AU final hero Noah Lolesio and James Slipper are in Queensland, while captain Allan Alaalatoa, Nic White, Tom Wright and Folau Fainga'a are in Canberra and expected to return next week.

McKellar unveiled his 36-man squad for 2021 on Wednesday, which included New Zealand import and former Junior All Black Tucker who has five Super Rugby caps for the Chiefs.

"He's a good player Tucks, he's been around, 26 [years old], he's got that experience, [he's] been involved in some pretty good programs with the Chiefs and the Blues," McKellar said.

"Played in Japan, overseas in Italy as well as a lot of ITM Cup. He's a lock, back rower who has battled injury, we've had players in the past that have come to the Brumbies that have battled injuries and we've always backed our program to get their bodies where they need to be.

"He's due for some luck and if we can keep him on the park he's certainly going to be a good addition to the group."

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A total of 28 players have been retained from last year's title-winning side while Tucker joins the likes of Reece Tapine and Archer Holz as new recruits to the club for 2021.

Five academy products have also been promoted.

"You've got to make sure that you develop them in the background when they're in our academy, and when they come into the main squad that we get them ready as soon as we can," McKellar said.

"Age is not something that we stress about it's their development and how quickly we can get them ready to play Super Rugby. That's something that we've done really well over the last number of years as we saw in 2020 with the likes of Lolesio.

"It's something that we pride ourselves on here at the Brumbies is developing them but exposing them at the right time.

"We've lost a few players but certainly not as many as we would've in previous years. It's nice to have that stability and be able to promote the boys as we've spoken about in the past."

The Brumbies will play two preseason trials before their title defence begins in Perth against the Western Force on February 19 ahead of a home blockbuster against the NSW Waratahs.