DON'T underestimate the importance of centre clearances for a second.

Fremantle coach Mark Harvey's comment after his side's round-10 loss to St Kilda sums up the feeling inside clubs: "That's the best one to win: the centre square."

You only need watch Melbourne's clearance specialist Brent Moloney at a centre bounce to know he believes that comment to be true.

He hunts the ball with ferocity. And he often wins it. "Obviously, with [ruckman] Mark Jamar in there, it gives me a lot of confidence to run at the footy. A lot of the time I know where it is going and I have the confidence in him putting it in that spot."

Moloney is one-quarter (albeit a very effective quarter) of a team within a team, a starting four pitted against the opposition's centre square specialists.

In that sporting furnace, it is not just see the ball, get the ball. The best starting fours - such as Geelong's or Collingwood's - work as a collective, blocking, hunting the ball, holding their position, tackling, and running to space.

"It's a mind game," Moloney said. "They (opponents) pretty much know where you are going to hit it as well, so it's all about timing, holding your ground and protecting space."

The purpose of systems in football is to multiply the value of the individual, increasing the team's overall output. An effective system is also more predictable, less susceptible to the ebbs and flows inevitably part of individual performance. Yep, a champion team surely will beat a team of champions.

Nowhere on the ground do we get a better snapshot of this reality than at a centre bounce.

It's a microcosm of the synchronised teamwork expected all over the ground.

Players need to switch in an instant from attack, to defence, to providing coverage, to receiving the ball. Those four who work together will be more effective than those working as individuals.

Some combinations attack better, others defend, others can neutralise the contest.

"It's like the quarterback's huddle [in NFL games] where they say the play and then break," Moloney said of the conversations that happen between starting fours before each centre bounce.

Champion Data knows it is the starting-four collective that produces the outcome, hence it measures the performances of starting-four combinations, measuring each quartet's clearances for and against, ability to create second stoppages, as well as scores for and against.

As well as seeing which combination attacks best, protects a lead or neutralises the contest, clubs can see which individuals work together well, who adds and who detracts from the team's performance in winning centre clearances.

These numbers might not attract as many headlines as individual clearances, but it is this data that interests midfield coaches. When assessing clearances, 'who' is as important as 'how'.

Eventually, good midfields learn the truth of collective action, understanding that it becomes easier to take in the four dimensions of football - space, your teammate, the opposition and the ball - and respond appropriately in given situations the longer you are around the same teammates.

Read how North Melbourne's Jack Ziebell explains what he faces at a stoppage and you can almost picture him taking in the four dimensions.

"Around the stoppages, it's mostly about just getting inside (between your man and the ball) at the right times. (Your opponent is) trying to get in front of you and you're trying to get in front of them, so you've got to work to run at the right time without getting too close to the ruckman, so it's a bit of a game," Ziebell said.

Although what he is describing sounds like the game of cat and mouse that sprint cyclists play at a velodrome, there's more than one variable in play.

"It's about using your body in ways that protect the space where the ball's going to go and there's also an element of which ruckman's going to win it so you have to have those bases covered, too," he said.

Change from an individual mindset to a collective one does not happen overnight. The comments from even the most team-oriented players such as North Melbourne star Andrew Swallow reveal the battle that occurs within everyone's mind.

"It's always nice to look up and see you have some nice stats," Swallow said.

"But in the end, it's about winning for the team, so it's a lot more enjoyable when you're winning even if your [individual] statistics aren't as great as they could be."

Admittedly, Swallow made a fair fist of turning things into a one-man show against Adelaide in round 11 when the ball appeared to follow him around at clearances, but it wasn't a coincidence that Levi Greenwood had returned a week earlier to bolster the midfield.

Swallow said midfield depth had a big impact. The return of Greenwood and Ryan Bastinac was critical to North Melbourne going from being competitive to winning consistently.

"Having Levi as well gives us a bit of extra size and he's got a great motor. So that allows us to rotate and really keep the pressure on at the source," he said.

The return of Tom Scully and Jordie McKenzie to Melbourne's midfield has been a big factor in the Demons' recent consistency, too.

"The more guys we can get through there the better off we can be," Moloney said.

Leading the competition in creating scoring opportunities is the North Melbourne combination of Todd Goldstein, Swallow, Ben Cunnington and Daniel Wells. But North also has depth, with Ziebell, Greenwood, Ryan Bastinac, Brent Harvey, Liam Anthony and Leigh Adams all capable of taking their turn in the centre square.

Swallow said players working through that space understand their roles: "We want to get blokes into space and get them free but, if we can't, we're happy just to kick it in as quickly as we can because you've got more chance of kicking into a one-on-one than into an outnumbered situation."

Emerging midfield groups at North Melbourne and Melbourne need time together to go from promising to damaging.

Ziebell said eventually the shift that happens is one where constant communication is required, with players reminding each other what their roles are at each stoppage, to one where less communication becomes necessary.

That's when the implied (often unstated) understanding that happens among great combinations becomes entrenched. In many ways, Geelong showed the way in this area. The more the Cats worked as a team, the more individual plaudits came their way.

Then Collingwood followed with a damaging group, combining to create more inside 50s a match than we had ever thought possible.

Those old pros, the Sydney Swans, remain as steady and as good as ever, while the Saints have struggled in this area in the absence of Lenny Hayes and Michael Gardiner, and are spending a year reinventing that space.

Now the challenge for those chasing the big five (Geelong, Collingwood, Carlton, Hawthorn and West Coast) is to develop experience and understanding to match those teams.

North Melbourne and Melbourne are the leaders among the chasing group that includes Richmond, Essendon and Gold Coast.

That's why coaches plead for time, for patience, for people to hold their nerve.

That's why North Melbourne and Melbourne know, regardless of results, the need for improvement is ongoing.

Moloney is relishing that prospect. He is a student of the stoppages who watches the best go about their business in order to learn how to enjoy the responsibility he and his teammates have to get the ball going in the right direction.

"It's a challenge every week. It's great. That's why you play."

The system at work
Early in the third quarter of last week's game between Port Adelaide and North Melbourne, there was a 15-second patch of football from the Kangaroos that was a good example of a perfect centre square clearance [and the important role each player had].

It is hard to imagine being able to script a scene better.

The ball was bounced in the centre. As it reached its highest point, Jack Ziebell moved and stepped in front of Matt Thomas, blocking him from the ball.

At the same time, Todd Goldstein outleaped Daniel Stewart, his left arm raised to tap the ball right towards Levi Greenwood, who had shaken off Travis Boak and was already on the move.

Greenwood's momentum allowed him to steal the ball from Matthew Broadbent's hands. Broadbent was static because he was worried about letting Andrew Swallow, a clearance master, near the ball.

Coming off the wing were Kane Cornes and Ryan Bastinac. Bastinac trusted Greenwood to get the ball and waited back, while Cornes had committed himself to stopping the charging Greenwood.

Greenwood handballed into open space and the ball landed behind Bastinac, who took possession and kicked on his left foot to a leading Cameron Pederson.
Greenwood, Ziebell and Bastinac kept running, giving Pederson several handball options.

In the vernacular, it is called a 'spread' and takes concentration, good decision-making and, when the lungs are screaming, courage to keep pushing.

Pederson handballed inside to the running Bastinac who kicked, this time using his right foot, to Aaron Edwards who marked in front of opponent Jackson Trengove.

Click here to see North's clearance work

Ziebell and Greenwood's running went unrewarded in terms of a possession, but anyone watching the game live - and particularly the coaching staff - would have recognised it because it showed individuals prepared to "run in case", a habit that turns good teams into great teams.

Swallow was the same, standing at Edwards' feet as he marked. The midfield had done what was expected.

"The quicker you can get it in, the more chance you have of having an even-number situation up the field," Swallow said.

"We're happy just to kick it in anyway and try to press in and hold the footy up in our forward half."

When the ball was bounced, there was 16 minutes, 35 seconds of the third quarter remaining. When Edwards took the mark, there were 16 minutes, 20 seconds left.

On the North Melbourne bench were Ben Cunnington, Daniel Wells and Leigh Adams, leaving the job in capable hands, resting, ready to take up the baton when it was handed to them.

In statistical terms, Goldstein would have recorded a hit-out, Greenwood the centre clearance and handball, Bastinac a handball receive and a couple of kicks, Pederson a mark and a handball and Edwards a mark, a kick and, because he never misses a goal. (Edwards has 24 goals and two behinds for the season).

Importantly, the Goldstein-Greenwood-Swallow-Ziebell combination had created a score by working together. The system had prevailed, employed with skill, discipline and fitness.

Belief in the system is the reason why North Melbourne coach Brad Scott said after the game: "Predictability is a big focus for us."

Best starting combinations by team
Adelaide: Sam Jacobs, Scott Thompson, Brent Reilly, Richard Douglas
Brisbane Lions: Matthew Leuenberger, Simon Black, Jack Redden, James Polkinghorne
Carlton: Robert Warnock, Chris Judd, Marc Murphy, David Ellard
Collingwood*: Darren Jolly, Dane Swan, Scott Pendlebury, Luke Ball
Essendon*: Tom Bellchambers, Jobe Watson, Sam Lonergan, Heath Hocking
Fremantle*: Aaron Sandilands, David Mundy, Matthew Pavlich, Matt de Boer
Geelong: Brad Ottens, Joel Selwood, Joel Corey, James Kelly
Gold Coast: Zac Smith, David Swallow, Michael Rischitelli, Gary Ablett
Hawthorn: Max Bailey, Brad Sewell, Sam Mitchell, Jordan Lewis
Melbourne*: Mark Jamar, Brent Moloney, Jordan Gysberts, Jordie McKenzie
North Melbourne: Todd Goldstein, Andrew Swallow, Jack Ziebell, Daniel Wells
Port Adelaide: Matthew Lobbe, Travis Boak, Hamish Hartlett, Domenic Cassisi
Richmond: Andrew Browne, Daniel Jackson, Dustin Martin, Trent Cotchin
St Kilda**: Ben McEvoy, David Armitage, Clinton Jones, Jack Steven
Sydney Swans: Shane Mumford, Jude Bolton, Kieren Jack, Jarrad McVeigh
West Coast: Dean Cox, Daniel Kerr, Matt Priddis, Scott Selwood
Western Bulldogs: Ben Hudson, Callan Ward, Matthew Boyd, Ryan Griffen

*Jobe Watson, David Mundy, Aaron Sandilands, Darren Jolly and Mark Jamar are included, despite missing extended periods of 2011 through injury.
**St Kilda's clearance specialist Lenny Hayes played only two games in 2011.

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

This article first appeared in the AFL Record