The Swans coach said his side was outplayed and received its just desserts.
After starting well with four goals to one in the opening term, Longmire said the Swans didn't cope with the increased pressure the Power brought after the first break.
The telling statistic, Longmire said, was the difference in scores from turnovers: the Power won 60-3.
Just a fortnight ago, the Swans pressured Adelaide into countless errors at AAMI Stadium but they were on the other end of it this time, Longmire lamenting his players' poor skills.
"That was the story of the game," Longmire said of the scores from turnovers.
"When we had our turn, we weren't able to make them pay and on the flipside they were able to get the ball … and be efficient going forward.
"They tackled hard, they used the ball well and if you come up against a team that does that consistently well over four quarters, you need to be doing the same thing.
"We got what we deserved.
"Port Adelaide turned the pressure up and I don't think we handled it as well as we should have."
Longmire was at least pleased with the return of star forward Kurt Tippett.
The 26-year-old made an immediate impact, marking and then converting just 15 seconds into the opening quarter.
He imposed himself on a number of contests and while he appeared out of position at times, there was enough to see to encourage his coach.
"I thought he looked pretty good … two (goals) two (points) is a pretty reasonable return," he said.
"He looked pretty clean, the conditions were obviously difficult but when he got his opportunities he took a couple of marks and was pretty good at ground level."
Longmire said he had planned to sub Tippett out of the game, but a jarred knee to Adam Goodes meant his plans were forced to change.
Goodes landed awkwardly in the third quarter and appeared in some discomfort, but Longmire said it looked a minor injury.
