A defiant John Longmire says you "don't have to be Einstein" to see that runner restrictions are disadvantaging young teams, with the Sydney coach hopeful "some sanity prevails" on the issue.

Since the start of this season, runners have only been allowed to come on after a goal has been kicked and must exit the field before play restarts.

The move has proved unpopular with a number of AFL coaches, including Western Bulldogs coach Luke Beveridge who said he felt "helpless" when the rules were first used during this year's JLT Series. 

Longmire again raised the issue following the Swans heartbreaking one-point loss to Fremantle on Saturday night, arguing the controversial change had been a problem for his team all year.

He said there was no doubt the restrictions were disadvantaging the competition's younger sides.

"You don't have to be Einstein to work that out," Longmire said.

"We've got young kids out there that are running around … trying to think about everything in the game, including just trying to get their hands on the footy, plus doing the rotations themselves and trying to think through some (tough) situations.

"It clearly is not going to change before the end of the year, so we just have to deal with it and make sure our players learn from it. And they'll learn from it pretty quickly."

Longmire said he just wanted to be able to help his players and called for "sanity to prevail" on the issue.

"I'd love it to (be brought back to) what it was but I'm not sure (the AFL will) say they were wrong," Longmire said.

"I just hope some sanity prevails because coaches aren't there completely to ruin the game and when you've got a really young team, you'd like to be able to help them a bit."

The Swans coach praised his side's consistent effort during their loss to the Dockers, but lamented poor skill errors that proved costly.

Longmire said his young players would learn from the nailbiting loss, which the Swans led until Fremantle kicked two late behinds in the dying minutes.

"They'll be some things we'll be able to show our players. We're the youngest team for the round this weekend, we're younger than Gold Coast," Longmire said.

"We'll come out of that looking at some areas where you're in tight situations … and you need to think clearly through some of those things.

"Until you've actually lived it, it's very hard to put experience into those blokes. So they'll get that experience from tonight."