COLLINGWOOD coach Mick Malthouse says people will turn off football if games continue to be one-sided.

Facing the media after the Magpies obliterated Port Adelaide by 138 points at AAMI Stadium on Saturday night, Malthouse said the gulf separating clubs at opposing ends of the ladder was too wide.

"As a purist, you like to see games of football that are relatively even," Malthouse said.

"I just think the score lines at the moment in AFL football have to be a worrying trend to the AFL."

The average winning margin of three games played on Saturday (Geelong defeated Gold Coast by 150 points, Carlton defeated Melbourne by 76 points, and Collingwood won by 138 points) was 121.3 points.

"I suppose, if you are going on the trend of the year, we should have won the game. And we did," he said.

"But we are seeing far too much of this. I just think we might murder our game in its present state.

"This is not going to bring people to the football. Most people would've turned that off."

Collingwood dominated the Power from the outset, booting the first 12 goals of the game before Port finally found the big sticks in the dying seconds of the second term.

By then the reigning premier was in cruise control, with eleven players gathering 18 disposals or more and six Magpies finishing with multiple goals. Collingwood had 44 scoring shots to Port's six, further illustrating the visitors' dominance.

The records also tumbled at AAMI Stadium, as the Magpies held the Power to their lowest total in AFL history and handed Port their heaviest defeat since entering the competition.

The 138-point margin was also Collingwood's third-highest winning margin, ousting the Pies' 128-point thrashing of St Kilda in round 17 of the 1901 season.

Malthouse said that the AFL's plans to introduce free agency into the competition will only exacerbate the gap between the strong and the weak.

"Believe me it's going to get worse. It will get worse when free agency comes in," he said.

"History just shows that, in any sport, players who want to change clubs don't change clubs necessarily for money, they change for success. It makes the top sides stronger and makes the bottom sides weaker.

"Unfortunately I think we are going to create something that is not what is ideal for the competition.

"[But] every dog gets his day. We've travelled before and been belted before over here, so I suppose things have turned around."

Max covers news from AAMI Stadium for afl.com.au. Follow him on Twitter: @AFL_MaxPhillips