Sydney's elite leaders have been stung by criticism over their scarce support for young teammate Callum Mills and have vowed to never let it happen again.
Last year's NAB AFL Rising Star was physically and verbally targeted during last week's shock loss to Carlton at the MCG, and the Swans have been heavily scrutinised for what was seen as a lack of protection and care for the young defender.
Parker said the Swans did let Mills down and it wouldn't happen again.
"That shouldn't happen to a second-year player who has played less than 50 games and we were disappointed with it, but we'll make sure that it never happens again," he said.
"We need to make sure, especially with a young bloke like that, that he's taken care of.
"You don't want to be stupid about it and give away free kicks, but we as a team need to stamp our authority and say that’s not on, and we're not going to accept that.
"There's obviously a fine line that we can’t cross to do things outside the laws of the game, but what stands up for us is the way we attack the ball, the way we attack the man when we tackle, and having that real physical edge about us.
"It's not always about buying into the little niggles that go on, it's about making teams aware that we won't put up with it, and the next contest we'll go twice as hard."
Parker echoed the sentiments of coach John Longmire, who on Wednesday said the last-quarter incident was indicative of the way the Swans are going about their footy this year, and is one of the major reasons they sit on the bottom of the ladder, winless after six rounds.
"We're playing well in patches, and we're helping each other out in patches, then at other times we're forgetting about our teammates a little bit," Parker said.
The 2016 All Australian and Brownlow Medal runner-up is one of a number of experienced Sydney stars slightly down on form this season - his average possessions per game has dropped from 26.9 to 23.2, and he's kicked just two goals from six games after booting 25 last year – and admitted even he'd ducked into self-preservation mode at times.
"At times if you're low on confidence you probably go back into your shell and it's nearly impossible to stop that, but it's the worst thing you can do," he said.
"In my case I wasn't in my best form at the start of the season and I guess you look at what you need to do (to find form), but we need to remember that we're all in this together, we need everyone on board, and we need to get better together.
"It's the most disappointing start to a season I've had since coming to the club, but the boys are up for the fight and know what we have to do to get our season back on track."