Nic Naitanui's controversial suspension for a dangerous tackle is confusing for players, according to North Melbourne assistant coach Josh Drummond, who has called for greater consistency around whether it's the tackler's action or the outcome that dictates his penalty.

Naitanui was suspended for one match for a tackle on Karl Amon last Saturday that left the Port Adelaide midfielder with a mild concussion.

The West Coast ruckman challenged his penalty at the AFL Tribunal on Wednesday night, arguing he had not breached his duty of care to Amon by tackling with excessive force.

However, the Tribunal upheld Naitanui's suspension, sparking a wave of criticism by past and present players.

North captain Jack Ziebell described the decision as "unfathomable".

Drummond told reporters on Thursday he had seen tackles by Naitanui earlier this season that had looked "very similar" to the Amon one but were cleared by the match review officer.

"(Naitanui) is just a big strong guy, like 'Maj' (Majak Daw). Maj has laid some really strong tackles the last couple of weeks and we're applauding him for it, but if coincidentally through the action the player's head touched the ground or hit the ground, Maj is in trouble," Drummond said.

"When the outcome dictates the penalty, then we're in trouble. If on one side we're applauding them, then the next if their head hits the ground we're suspending them, then as a player you're going, 'What do you want?'

"I think some consistency around whether it's the actual action that's the issue or the outcome would help everyone."

The AFL's legal counsel, Jeff Gleeson QC, told the Tribunal that Naitanui, at 110kg, had to remember he was roughly 30kg heavier than Amon when exercising his duty of care, arguing players regularly had to "compute" their height and weight compared to an opponent's ahead of contests.

Asked whether "big blokes" such as Naitanui and Daw had a duty of care to tackle differently to smaller and lighter players, Drummond said: "I don't subscribe to that."