FAILURE to win the big moments cost his side against another top-four side on Saturday afternoon, according to West Coast coach Adam Simpson.
The Eagles went down to the Swans by 39 points at the SCG despite being in front through the third quarter of their first match at the venue since 2010.
West Coast looked in a good position when Elliot Yeo snapped truly 10 minutes into the term, but the Swans kicked the next six goals of the game to pull away.
A frustrated Simpson said the Swans' leaders stood up all over the ground when it mattered most.
"We knew it was going to be an arm wrestle, we were prepared for that and I thought we did start well but critical moments really cost us," he said.
"But when we responded in the third (quarter) there were three or four goals we conceded on the back of critical one on one contests and they made us pay.
"I think they should have won by more to be honest.
"I thought our forwards got beaten today, and there were definitely stages that we thought we could have handled better.
"We thought that while we were in the game, (but in) the last 10 minutes of the third there were danger signs.
"Then the game got away from us halfway through the last and once again some of the things we failed on wasn't the personnel, it was collectively.
"I think in the last quarter we had 19 inside 50s to 11 and we didn't kick a goal so credit to Sydney they're a very good side."
WATCH: Adam Simpson's full post-match media conference
Simpson refused to concede that his men have an issue when playing away from Domain stadium, despite the Eagles losing four and drawing one of their past five road trips.
Of those five games, West Coast has lost to the Swans, Adelaide and Hawthorn (twice), as well as drawing with Gold Coast. The Eagles' most recent road win came against Collingwood at Etihad Stadium in round 16 last year.
The West Coast coach also said that his side's form away from Perth was nothing to do with their preparation.
"Losing is a concern wherever you are, we've played Hawthorn and Sydney away this year and we've lost," Simpson said.
"I thought (the) Hawthorn (game) we barely even showed up.
"There's different thoughts going through my mind today, but if we're going to be successful we've got to win interstate, so that's the reality.
"At the moment every team we play away is a good team and every team we play at home is a good team, it's a really even competition.
"I'd be really disappointed that if halfway through the third quarter we fell away because of what we did yesterday or on the plane.
"We were in the game up until a certain point where we weren't so we'd be jumping at shadows to say it's something to do with our preparation."
