The Kangaroos slammed through the opening five goals of the last half and turned a 15-point advantage at the main interval to a commanding lead of 34 points at the final change.
West Coast mounted a challenge of sorts in the final term, but wasn't able to seriously threaten, hitting the post on three occasions.
The 16.12 (108) to 11.9 (75) result moves the Kangaroos to 6-7 and keeps the club in touch with eighth spot, held by Sydney, which is 6-6 and with a game in hand.
The Eagles (5-8) have seen September action for the last two years but, barring a significant reversal of form, particularly away from Subiaco Oval, they will struggle to participate in the 2004 post-season.
Under pleasant skies on Sunday afternoon, the Roos produced a supreme team effort that placed the Eagles under suffocating pressure throughout.
Livewire Brent Harvey finished the match with four goals and 20 possessions in a best-on-ground performance, with Shannon Grant and Anthony Stevens also accumulating plenty of the footy.
They were also well served in the backline, with Leigh Colbert seeing off a host of centre-half forwards and Glenn Archer attacking the footy fearlessly.
The prolific midfield rotations from the Roos continued to deny time, space and, as a result, opportunity for the Eagles' runners to exert much influence on the contest.
That harassing and relentless pressure brought about uncertainty and fumbling from their opponents with many of West Coast's attacking thrusts coming undone via an inaccurate handball, poor options or rushed kicks directly to a Kangaroos player.
In terms of the main match-ups, Michael Firrito looked after Daniel Kerr, Brady Rawlings never left Chris Judd's side and Shannon Grant often forced Ben Cousins into error.
But in a positive for the losers, forward Andrew McDougall has continued his recent improvement, booting three goals. Veteran Phillip Matera, playing his 150th game, also managed three but the pair lacked support.
The Kangaroos were on top across half back at the start of the game but led by only three points at the first break after the Eagles kicked the last two goals of the opening term.
Mark Porter began to assert some control in the ruck contests, which allowed the Roos, through the dominant Daniel Harris, hard-working Stevens and skilful Grant.
In a 16-minute period midway through the second term when West Coast's star midfielders Ben Cousins and Chris Judd were off the ground and ruckman Dean Cox resting, the Roos broke clear, kicking four goals on the way to a half-time lead of 15 points.Kangaroos coach Dean Laidley was pleased his team was able to stay in the hunt for the finals by playing to instructions throughout the four quarters.
"I thought they were terrific and very hard. The pressure they put on the opposition was excellent," Laidley said.
"I just think everyone walks away with a bit of confidence and good feeling about themselves and about the team."
"We're still in control of what we're doing. It's terrific to get a win and go into the break like that."
Losing coach John Worsfold didn't have many answers for his team's third quarter and overall performance.
"In periods they just cleared the ball too easily and when we did, it was under a fair bit of pressure."
"There was good pressure from the Kangaroos but there were a lot of non-pressured mistakes from us as well."
"It leaves me scratching my head about our up and down form, our away form. We keep talking about it but we've just got a lot of work to do and we'll keep plugging away at it."
In the next round, the Kangaroos take on Essendon and the Eagles host Geelong.
Kangaroos: 5.4 10.8 15.9 16.12 (108)
West Coast: 5.1 8.5 10.5 11.9 (75)
Goals: Kangaroos: B Harvey 4, Rocca 3, Harding, Grant 2, Rawlings, Harris, Brown, C Jones, Firrito 1
West Coast: McDougall, Matera 3, Kerr, Cousins, Seaby, Chambers, Sampi 1
Best: Kangaroos: B Harvey, Archer, Colbert, Simpson, Grant, Harris, A Stevens
West Coast: Fletcher, Morrison, Cox, Chambers, Glass
Injuries: Kangaroos: Firrito (jarred ankle)
West Coast: None
Changes: West Coast: Staker replaced in the selected side by Morrison
Reports: None
Umpires: Head, James, Stevic
Crowd: 8542 at Manuka Oval, Canberra
