Assistant coach Darren Crocker says North's midfielders have improved significantly since the club's round 10 win over West Coast at Blundstone Arena earlier this season.

The midfield will again be an intriguing battle when the sides meet in Saturday night's preliminary final at Domain Stadium.

Crocker said the Roos had "evolved" and were "a better team" since their 10-point win over the Eagles in Hobart.

"We're understanding a little bit more of what it takes for us to be a really good team and play at our best," Crocker told NMFC.com.au.

"We've been able to settle players down into roles that really suit them for the team and there's also a bit of belief within the group as well."

Among those to settle in their on-field positions and lift their output in the Roos' midfield is reborn tagger Ben Jacobs and hard-running onballer Sam Gibson.

Jacobs restricted Richmond captain Trent Cotchin to nine disposals in the elimination final – Cotchin's equal lowest tally on record – before keeping Sydney Swans ball-winner Daniel Hannebery to 20 touches last week.

Gibson has also elevated his game in the finals series, limiting Tiger Brandon Ellis to 10 disposals and stopping Swans speedster Lewis Jetta in the semi-final.

Crocker said the match committee was yet to formally decide which opponent the pair would be assigned this week.

"The beauty of the first two finals has been that the coaches have done a really good job in identifying the opposition's strengths, and with a lot of our planning, we've been able to take away a few of those strengths with match-ups," he said.

"As a match committee, we're still deciding which way we'll go this week with those guys."

Three possible match-up options would likely include All Australian midfielders Matt Priddis and Andrew Gaff, and fellow onballer Luke Shuey.

Crocker said the trio each strengthened the Eagles' midfield group, complementing the likes of Chris Masten, Elliot Yeo and Matt Rosa.

"Priddis is more an inside player or plonks himself, and does get on the move a little bit but doesn't have a lot of speed," he said.

"Shuey is more of a burst player, can get on the move, can hit through the stoppage a lot more and can penetrate the game.

"And then you've got Gaff, who has developed his game where he goes a little bit inside and plays outside, and he's been doing that more this year than previously."

One direct match-up is guaranteed, however, with two of the competition's premier big men, All Australian Todd Goldstein and Nic Naitanui, to battle for ruck supremacy.

"'Nic Nat' is obviously very athletic, a terrific jump, very powerful, follows up well, can win his own ball and he averages a number of clearances himself as a ruckman," Crocker said.

"(He) can push hard forward and take a contested mark, but in saying that, Goldstein's work around the contest this year has been really strong.

"Goldy's really developed the ability to take some marks on the outside when the game breaks open and kicks down the line."

Crocker said ball-winner Ben Cunnington had been a standout in each of the six finals appearances he had made so far, dating back to the 2012 elimination final loss to the Eagles.

"If you go back in history, I can't really remember him playing a bad final since he's come into it," he said.

"It looks like he thrives on the big stage even though he's pretty unassuming and quiet sort of type, but I think he really looks forward to the challenge pitted against some of the better midfielders."