A burst of blowout wins should worry AFL bosses, Collingwood coach Mick Malthouse says.

And the Magpie mentor warns the yawning gap will widen with the introduction of free agency.

Collingwood thumped Port Adelaide by 138 points on Saturday night - a record losing margin for the last-placed Power, who kicked their lowest ever score, 3.3 (21).

The Magpie mauling came as Geelong again won by 25 goals or more, thrashing Gold Coast by 150 points.

"The scorelines at the moment in AFL football, I think, has to be a worrying trend for the AFL, it has to be," Malthouse said.

"This is not going to bring people to the football.

"Do you get any delight out of it? No ... we're entertainers not masochists."

Malthouse reckoned "every dog has his day".

"But as a purist you like to see games of football that are relatively even," he said.

The trend of massive margins wasn't "isolated" so couldn't be dismissed, Malthouse said.

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

"History just shows 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 the bottom sides weaker.

"We have seen that in European soccer, we have seen that with other codes, and unfortunately I think we are going to create something that is not what is ideal for the competition.

"... This (margin) is not isolated ... we are seeing far too much of this."

After toying with Port, Malthouse noted Collingwood was the league's big spender and the Power, recently bankrolled by the AFL to ensure survival, was among the poor.

"I'm not too sure how much of the salary cap they pay, we know we pay the top," he said.

Malthouse also called for actual game time to be reduced, questioning why 20 minute quarters usually went 30 minutes.

"The game is too long, just far too long," he said, adding impartial footy fans watching the Port-Collingwood game would have switched off.

Malthouse said there many options to shorten games, but declined to elaborate.

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