On a day when Perth was hit by a once-in-a-five-year storm before conditions calmed during the game, West Coast kicked eight unanswered goals either side of halftime to soar to a 12.13 (85) to 8.7 (55) win in front of 37,623 fans.
The match was Essendon's first since sacking Scott during the week, and they fronted up against the Eagles nursing a 16-player injury list.
That became 17 in the first quarter when May dislocated his right shoulder after being cleaned up by teammate Nate Caddy in a marking contest.
"There was a dislocation, I don't know much more than that at the moment," Essendon interim coach Dean Solomon said.
"He was in our team meeting, so he's fine, but length of time and whether it's surgery or not surgery, I have no idea at this point in time."
Apart from brief patches and some late junk goals, Essendon barely troubled West Coast.
Even the Bombers' 44-23 dominance at the clearances didn't translate to any sort of authority.
"The clearance number was obviously a big deficit tonight, and this will sound silly, but it was never a massive threat in the game," Eagles coach Andrew McQualter said.
"We outscored them from stoppage and we forced them to spots we wanted to.
"We'd love to win more of the ball, but I thought our pressure was able to handle most of that."
The result improved West Coast's record to 4-8, already a marked improvement on last year's one-win wooden-spoon campaign.
Essendon (1-11) are in grave danger of collecting this year's spoon.
Harley Reid (24 disposals, one goal), Tim Kelly (28 disposals, 554m gained), Milan Murdock (three goals, 19 disposals) and Jake Waterman (three goals, nine marks) played important roles for the Eagles.
But best-on-ground honours went to Reuben Ginbey, who was a star in defence and kept Caddy goalless for three quarters.
The Bombers forward kicked two goals late in the game - one when Ginbey was off the ground - but had no other influence on the contest.
For Essendon, Archie Roberts (30 disposals, 570m gained), Zach Merrett (28 disposals, one goal) and Sullivan Robey (nine clearances, 19 disposals) found plenty of the ball in a losing cause.
Solomon pulled a surprise move by playing Ben McKay at full-forward, but he was non-existent early as West Coast registered the first 10 inside 50s of the match while kicking with the breeze.
The Eagles led 17-1 by quarter-time, but Essendon made the most of the strong breeze early in the second term and even had several opportunities to snatch the lead.
Their missed chances proved costly, with West Coast's counter-punch netting three important goals as the Eagles entered halftime with a 20-point buffer.
The highlight of the second quarter belonged to Reid, who sold a dummy and shook off two tacklers while surrounded by players before snapping truly to send the crowd wild.
West Coast iced the game with a dominant five-goal burst to start the third quarter as the lead ballooned to 53 points.
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