AT AEGIS Park last week, Ben Cunnington had just started an interview with afl.com.au when Scott Thompson sneaked up and grabbed him from behind.

"You know the rules, 'Cunners', talk the backmen up," Thompson said before walking off laughing.

As much as Thompson was joking, his quip was also a sign Cunnington has been accepted as a member of North Melbourne's back six.

The No. 5 pick in the 2009 NAB AFL Draft has played most of his 29 AFL games in North's midfield, but since Daniel Pratt broke his right thumb in round 10 against the Sydney Swans, he has played in defence.

Defensive groups can be notoriously tight-knit. In the defensive 50, any slip-up can cost your side a goal, so defenders have to know they can trust each other to do the right things, and work as a team, when the pressure's on.

"The back line is definitely a really strong group and has been for a few years now," Cunnington says of North's defence.

"They seem to have accepted me and I'm privileged to be a part of that. Once you get accepted there, they've got your back on the field and off the field. They just help you wherever they can.

"And having experienced guys like Scotty 'Thommo', Brady [Rawlings] and Michael Firrito, it's just good to play alongside them - you learn a lot."

Cunnington is "loving" his time in defence and says it has helped ensure he's not pigeon-holing himself as a one-position player. "That's pretty important these days," he says.

Although he spent some time at half-back as a junior, Cunnington says back then he was given the licence to read the ball and do as he wanted.

But he feels the discipline required to play in defence in the AFL will help his game, in particularly his focus and consistency.

"I find in the midfield I sort of get stuck in the one gear, just running around," Cunnington says.

"The game is of such a high standard and is played at such a high speed it's easy to drift in and out of the play.

"But when I go back to defence, it's do or die. Down back you've always got to be on your toes, otherwise you give up a goal for the team. So I think that helps me find more consistency for the team."

When Cunnington talks about drifting in and out of games, you need to remember the second-year player, who turns 21 on June 30, has a reputation for being notoriously hard on himself. Read his regular blogs on kangaroos.com.au and he'll invariably point out his errors from his most recent game.

Cunnington says he has had high expectations of himself ever since he was a boy. "I'm just always trying to get the best out of myself," he says.

But where Cunnington would dwell on his mistakes in the past, he now tries to move on and focus on the next contest. In that regard, Daniel Wells, his mentor at North, has been a great help.

"I've learnt heaps from Daniel," Cunnington says.

"He's a shy type of person but just watching the way he goes about it on and off the field is invaluable. I think we're pretty similar and I think he sees that too, so he's taken me under his wing.

"And when things don't go my way he's the first to get over to me and say, 'Just keep working on it, you'll get through'. It gives me confidence."

Similarly, Cunnington has not dwelled on former Sydney Swans coach Paul Roos' comments earlier this season that he and third-year midfielder Jack Ziebell were unfit.

The fact his two pre-seasons at North were severely disrupted by injury - in 2010 by a hot spot in his foot and this pre-season by knee problems - has not helped Cunnington in this regard. Not that he uses it as an excuse.

"The club and I know fitness is not my strength," he says.

"I'm always willing to recognise my weaknesses so I've been trying to work on my fitness and I feel I'm getting fitter each day."

It seems a safe bet Cunnington's single-minded approach will ensure he builds the endurance base he needs before too long.

When he does, you can also bet his backline 'brothers' will face even stiffer competition for his services from North's midfield.