North Melbourne list boss Brady Rawlings has addressed his club's apparent interest in pursuing an uncontracted defending duo this off-season, as he reaffirmed the Roos' desire to upgrade in their back half.

The Kangaroos appear to be examining their backline options as they seek to compensate for the loss of key-position stopper Ben McKay, who departed Arden Street for Essendon during this year's free agency period after expressing a desire to leave.

North Melbourne had been linked to previously delisted Sydney Swan Toby Pink, who was last AFL-listed in 2019, having not managed a game at the professional level.

Pink, who has been plying his trade as a key defender, is currently playing with Glenelg in the SANFL and is likely to be available to AFL clubs in November as a delisted free agent.

Rawlings, who first expressed his surprise at Wednesday's frenetic day of off-season dealings, detailed the Roos' potential pursuit of Pink.

"It was a crazy day, not something that would normally happen [on] Day 3 of trade ... It was as busy day as I've had in Trade Period," started Rawlings viaย AFL Trade Radio.

"We've been in the key defender space all of this year ... We've scoured the country with AFL-listed players that might not be getting an opportunity with their club, and we've scoured the State Leagues.

"Watching Toby perform at Glenelg, his game really came on as a key defender."

Rawlings also revealed North Melbourne's genuine interest in off-contract Richmond defender Bigoa Nyuon, who can sign anywhere this off-season.

Despite confirmation of their interest in the Tiger, though, Rawlings reminded that the athletic backman hasn't been offered a deal by the Roos as yet.

"Yeah, there's some interest from our end in 'Biggie'," said Rawlings. "He's a very athletic player, can play in [the] ruck or key defence.

"We're just in discussions at this stage, [he] hasn't been offered a contract just yet."

Nyuon, who can exercise his rights as an unrestricted free agent his year, has not been offered a contract extension by the Tigers this off-season.

This year's free agency signing period concludes on Friday at 5:00 PM (AEDT) before the delisted free agency window opens on Wednesday, November 1.