ON ONE level, what led to Drew Petrie's five-goal last quarter heroics against Richmond at the MCG on Sunday is easy to determine.

He kicked straight, took marks and was on the end of one chain of handballs that stretched the length of the ground like a daisy chain.

It was nothing new from Petrie either, a player who can charge at times like a hot golfer making birdies on the back nine.

In 2007, he kicked six goals at the same City End in just 20 minutes in an opening quarter blitzkrieg against the Western Bulldogs at the MCG (the record for goals in a quarter is eight, a figure achieved five times).

While you will never hear his name in the same sentence as a million bucks, at times you wonder why.

It's probably because he is as unfashionably effective as an old Holden.

To the man himself, the reason for the match-winning burst was clear enough: his performance was a function of what his teammates did further up the field.

The humble Petrie understands better than most that he relies on the right mix of players around him to excel.

Examining what that mix is reveals North Melbourne's adaptability both over time and during games as it matures under Brad Scott.

In the first 10 rounds, Petrie kicked 21 goals and appeared down on form. What he lacked however was forward support.

In round 12 against Gold Coast, North recalled Robbie Tarrant and then a week later Lachlan Hansen was re-introduced to the forward 50 following a season interrupted with injury and suspension.

In the six-game period since round 12, and against good opposition, Petrie has kicked 22 goals (he has 43 for the season) to be the AFL's second highest goalscorer for that time.

The three tall forwards have combined to kick 42 of North Melbourne's 101 goals.

From sitting 16th for scores per inside 50 from rounds 6-10, the Kangaroos have moved back to a more respectable ninth for that measure in the past six rounds.

"It kind of stretches opposition defences when there are three talls running around," Petrie said. "The fitness of both Lachie (Hansen) and Robbie (Tarrant) is outstanding and they have both got good pace and good strength as well and the three of us are working well together."

Such overall trends are nice but at three-quarter time on Sunday it was clear the mix wasn't working against the well-drilled Tigers.

The trio had two goals (both from Petrie) between them and Richmond was launching attacks from defence.

The Kangaroos had to respond.

Scott benched Tarrant and replaced him with nimble crumber Matt Campbell, who had been the substitute.

Campbell's presence allowed Petrie to attack the contest without being as concerned about the rebounding effect of his opponent, Alex Rance, when the ball hit the ground.

Free to fly, he took two contested marks in the last quarter, which led to goals and put North Melbourne back in the game.

Petrie would say later that Campbell's chasing and tackling pressure (and handy goal) was important to the way the forward line functioned late in the game.

Petrie's effort was also a reminder that taking contested marks inside 50 appears to be a feature of good teams.

Eight of the top 10 teams at taking grabs under pressure inside their forward 50 fill the top eight spots in the ladder.

Petrie has taken 17 from 16 games in 2012 to sit eighth in the AFL for a statistic Collingwood's Travis Cloke continues to dominate (with 28 contested marks inside 50).

North Melbourne sits eighth on the table of contested marks inside 50 and seventh for goals from contested marks.

Petrie is one of the few men left that the coach can confidently seek to change the game by giving him space deep in the forward 50.

If that is what the circumstances of the game demands.

While Petrie will never blow his own trumpet, North Melbourne, with support now at ground level and roaming outside the arcs, is a team getting closer to having more than one way to unleash Petrie's talent.

Stats supplied by Champion Data

The views in this article are those of the author and not necessarily those of the AFL or its clubs.