Demetriou spoke for the first time after Melbourne was hit with a $500,000 fine for what the league declared was management prejudicial to AFL ethics.
Demetriou continued extraordinary rhetoric from his administration that Melbourne's big fine was not for tanking and deliberately losing games.
Former Demons head of football Chris Connolly and then coach Dean Bailey were hit with significant bans from their industry jobs.
Connolly is out for a year and Bailey for four months after they were found guilty of manipulating team selections against the best interests of winning, while Demetriou and his high-profile deputy Gillon McLachlan claim the breaches are not tanking.
Demetriou finally offered a form of official definition for the term “tanking” where McLachlan declined to in his baffling media conference on Tuesday when announcing sanction on Melbourne and Demons staff.
“Tanking is not performing on your merits and not trying to win the football match,” the league chief explained on Melbourne talkback radio 3AW.
“I know there are some people that are questioning the decision, this is a result of an eight-month investigation and you can only prove things on evidence.
“There is nothing to substantiate a tanking allegation.”
Demetriou has repeatedly and steadfastly refused to concede that tanking exists in AFL ranks, despite numerous claims of clubs manipulating lists and late season ladder finishes to obtain strong early draft selections.
Demetriou and McLachlan are adamant that Bailey and Melbourne players did not deliberately coach and play to lose games late into the 2009 season.
An extensive AFL investigation into claims that Melbourne deliberately lost games found that Bailey was “pressured” into resting players and putting others into positions foreign to them by Connolly as the Demons headed toward a last-place finish with only four wins and priority draft pick as well as first choice in the selection process.
Demetriou defended the controversial practise of clubs resting players late into seasons.
“That Dean Bailey rested players, there are other clubs that have rested players,” Demetriou continued.
“He rested players because he felt under pressure from comments made by Chris Connolly at a particular meeting, that there were several other people at, who attended that meeting.
“He rested players in pre-planning.
“But on match-day, he did everything in his power, as did the players and we don’t have evidence otherwise to suggest that he didn’t try to win the football match.
“There wasn’t any evidence to support and there was lots of players interviewed, I assure you, that supported that no-one out on the football field wasn’t trying to win that football match.”