IT IS no surprise that Geelong has had the best-performed defence over the past two seasons. The Cats concede, on average, only 75 points a game. At the other end of the scale, Melbourne this year has averaged having 118 points kicked against it.

Basically, the same seven players line up each week in the Geelong back half. Veterans Matthew Scarlett, Darren Milburn and Tom Harley are there to support the younger Josh Hunt, Andrew Mackie, Harry Taylor and Corey Enright. Of course, the back-line boys get great support from a forward line and midfield that pressures the opposition and prevents an avalanche of leather going into their area.

What is intriguing, though, is the way the Geelong back line operates. For years, the rule in football has been that you play your best defenders on the other team's best forwards. But Geelong has turned that theory upside down. The Cats try to free up their best defenders to be attacking rebounders, and give the lesser lights the responsibility to play tight on the opposition big guns. It's generally considered that Scarlett is Geelong's best backman. Some say he is one of the best full-backs of all time. Over 11 seasons and 200 games, he has played on the best forwards. But not now. Because of his amazing ability to read the play and create, the Cats try to free him up.

Evidence last year's grand final. Port Adelaide's most experienced and accomplished forward was its captain Warren Tredrea. Milburn played on and controlled Tredrea. That left Scarlett to play on Justin Westhoff, a skinny 20-year-old who was playing only his 16th AFL game. The boy was overawed and had only the four kicks and went goalless, while Scarlett, with 29 disposals, was his team's highest possession-getter. It was excellent coaching by the Cats to maximise their talents.

Last Saturday night in Sydney, we again witnessed the Cats' brains trust in action. Scarlett and Milburn were not playing. So who would play on Adam Goodes, who kicked eight goals a week earlier, and Barry Hall, who had kicked four? Both Swans stand 194 centimetres. Logic suggested the experienced and tall Harley and Mackie. But no. Josh Hunt, who is nine centimetres shorter than Goodes, was sent to the dual Brownlow medallist, while Taylor, in his first season and 10 kilograms lighter than Hall, stood "Big Bad Bazza".

The reasons for this were many and varied. Some worked and some didn't. It enabled Harley and Mackie to play on lesser lights and sometimes no one at all, when their opponents left the Sydney forward line to congest the Geelong forward line. Harley was able to push back and help Taylor on Hall and Hunt on Goodes, which he did to great effect. Harley leads the AFL for marks off the opposition's boot. He "turns the tide" if you like. Harley takes these marks because he reads the play so well, is often free of an opponent, and, of course, has skill overhead and displays great courage to back back.

So on Saturday, Harley and Mackie got a heap of ball to rebound with great effect. Hunt took up the challenge on Goodes and was very effective limiting him to a two-goal game. That effort adds another string to Hunt's bow.

For Taylor, however, it was a nightmare. Hall beat him in every one-on-one contest. Hall took 15 marks, nine of which were contested, and kicked five goals. But Geelong could afford to live with the problem because it had control of the game. Taylor got a bath, but some invaluable experience.

The move of the night, however, was that of 171-game veteran Joel Corey from the midfield to help out in defence on the half-back line. He was set to play on Ryan O'Keefe, who is a wide-roaming star. Corey sacrificed his own attacking game to lock down O'Keefe to his worst game of the season. Corey still amassed 28 disposals and was best afield for mine.

The sixth member of the Geelong defence was Enright. Strong-bodied and courageous and nearing 150 games, he leads his team in defensive rebounds.

Atttacking defenders give us exciting passages of play. And no one does it better than the Cats.

TURNING THE TIDE

Marks from opposition kicks

Tom Harley (Geel) 55

Jarrad Waite (Carl) 45

Brian Lake (WB) 35

Sam Fisher (St K) 33