Defender Michael Firrito says North's defence is aiming to "take the game on and be more aggressive" in the second half of the year.

The 31-year-old has taken part in every game this season in a backline that has welcomed forward-turned-defender Robbie Tarrant to great effect.

But Firritto said the back six's form had mirrored the whole side's performances this year.

"Our form as a backline has reflected how the team's going. Our good has been quite good but then we've let teams in in little patches and that's cost us," Firrito told NMFC.com.au on Wednesday.

"We're starting to get our backline together now and we'll go from there.

"I don't sit here happy with how things are going so I'm really determined and eager to really turn the season around."

Although Firrito could not pinpoint why North's form had fluctuated in the first half of the year, he said the team would have to tighten up areas all over the ground.

"I don’t think it's one or two things. When you talk about defence, it comes from right over the ground so, now more than ever, if one person is not playing their role it all falls apart," he said.

"We've regrouped and gone over a lot of things and hopefully you'll see a more consistent side come the second half of the year."

The 242-gamer said North's defence would need to display a ruthless attitude in a bid to recapture its 2014 form.

"We have to take the game on and be more aggressive, be able to turn the ball over and win it back quicker than what we have," Firrito said.

"That's what we were really good at last year, and even last year, it didn’t come straight away either – it took us a little bit of time to get it all together."

This weekend's encounter against Gold Coast marks Tarrant's 50-game milestone after being recruited with selection No.15 in the 2007 national draft.

Firrito said Tarrant's transition to the back six in the pre-season had begun to bear fruit.

"He was a high (draft) pick so we knew he could always play and he's shown it, he just couldn’t get a clean run," he said.

"He's come in and made a difference straight away."

Firrito said Tarrant's impending milestone would have a greater significance than your average 50-game achievement, considering his well-documented injury history.

"He had quite the surgery last year on his lower leg and 'Taz' even had some doubts himself on how the surgery would go, but it typified what sort of character he is and the way he's bounced back," he said.

"Even though 50 games might seem like a little milestone, his holds more weight than the norm."