It probably would have taken more than absentees Harley Reid and Tom Barrass to save the Eagles, who were blitzed in the third term on Sunday in their AFL match against Gold Coast at Carrara.
Thanks largely to Suns co-captain Jarrod Witts, the home side dominated the ruck hitouts 63-18 and the centre clearances 19-7.
The Suns also comfortably won contested possessions 148-112 and had 67 inside 50s to 35.
But after trailling by 34 points at three-quarter time, West Coast were only three goals adrift with five minutes left, before losing by 37.
"Just that 15-20 minutes of resilience was all I needed to see to suggest they have some spirit there," Simpson said of their last-quarter rally.
"But we have a heap of work - around the contest was not up to scratch.
"It felt like we left too much up to too few and their good players played really well around that area."
Sunday was a step backwards for West Coast after successive wins.
Simpson said their poor contested work would be a focus this week ahead of Saturday night's home match against resurgent Essendon.
"The little wins we're chasing, we probably didn't get many of those today, but I did see a bit of resilience in the group," he said.
"We'll definitely look at this as a learning game. It won't be 'bring your mouthguards on Monday', but we have to get better at that contest part."
West Coast also lost the free-kick count 30-19 and Simpson, again, was blunt.
"We have to own that free kick count - from what I saw, most of them were there," he said.
"So, second to the ball, or a bit hesitant, or a bit of both, when you're desperate to try and turn things around sometimes you do those things.
"I'm not going to say it was ill-disciplined, it was just poorly executed."
West Coast will regain Reid, who was rested, and Barrass from suspension.
Simpson remains adamant that Reid needed the week's rest.
"Missing one game, but we get him for 22, you do it every day of the week," he said.
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