Swans speedster Lewis Jetta booted four goals, while midfielders Ryan O'Keefe (39 possessions), Dan Hannebery (42) and Kieren Jack (29) starred as Sydney's frenetic pressure helped lift them to the 18.13 (121) to 10.9 (69) triumph in front of 39,152 fans.
But it wasn't all good news for Sydney, with utility Lewis Roberts-Thomson taken to hospital after copping a hard but fair bump to the head from Eagles defender Jacob Brennan.
Roberts-Thomson fractured his cheekbone earlier in the season, and may require a stint on the sidelines given the latest hit to the head was the third of the year.
West Coast also have injury concerns, with forward Jack Darling subbed out in the third quarter due to a hamstring complaint.
The Eagles hadn't lost at their home venue since an Adam Goodes-inspired Swans beat them by 13 points in round three last year.
Goodes tallied just 17 possessions and one goal this time around, but Sydney boasted winners all over the ground in a performance that should put the competition on notice.
The injury and suspension-hit Eagles started the round in second spot but slumped to fifth following their fourth loss of the year.
West Coast, minus the likes of Quinten Lynch, Luke Shuey, Josh Hill, Josh Kennedy, Andrew Embley, Mark Nicoski, Mark LeCras and Beau Waters, stormed out of the blocks with the opening three goals of the match.
But the Swans soon woke from their slumber, kicking eight of the next nine goals to open up a 23-point lead midway through the second term.
West Coast fought back to reduce the margin to one point, but late goals to Mike Pyke and Jude Bolton gave the Swans a 15-point edge at the long break.
And from there it was one-way traffic, with O'Keefe the star of the show as Sydney put West Coast to the sword.
O'Keefe tallied 17 possessions in the third term, while veteran Jude Bolton booted two goals in the last quarter as the Swans cruised to their sixth straight win against the Eagles.
Daniel Kerr (31 possessions), Scott Selwood and Matt Rosa battled valiantly through the midfield, but Sydney ruckmen Shane Mumford and Pyke did well to nullify powerful Eagles duo Dean Cox and Nic Naitanui.
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