BOTH the Sydney Swans and Fremantle had fewer inside 50s than their opposition in the first week of the finals and won.

This is a rare event.

In 2012, the team recording fewer inside 50s has won just 25.7 per cent of the time.

But in the finals so far, the win-loss ratio is 50-50 when it comes to inside 50s.

It might indicate a slight shift in how finals are won.

No longer is the game just about keeping the ball locked inside 50, forcing repeat entries and waiting for the dam wall to burst. That congestion opens space for quick counterattacks.

Nor is it just about long bombs to a key forward, no longer as effective a strategy as it was in 2011. In that year, the team recording fewer inside 50s won just 22.4 per cent of games.

Get it in was the principle 12 months ago, with the style of entry less important and the average number of contested marks per game being up to levels not seen for 10 years.

Now it's about quality inside 50s to loose targets working back, forward or sideways into space, or quick clearances from stoppages that end with forwards winning a one-on-one marking contest.

An analysis of the marks inside 50 in the first week of the finals showed that most of the contested marks came directly after a stoppage or a centre clearance.

This was because the forward was one-on-one in the moments after a stoppage.

Fremantle were very good at this against Geelong. It took 22 marks inside 50 with most the result of smart kicks to players working hard into space. Geelong's defensive checking was ordinary in the first half too as Fremantle took 13 marks inside 50. Every single mark was taken on the chest. It was an extraordinary night in that respect.

The Swans were good at the other end, stopping Adelaide from taking marks inside 50.

This was a function of all over ground defence, that meant the kicker was under pressure and therefore kicked to the defender's advantage (or at least neutralised the advantage), and great aerial skill, a point made by coach John Longmire.

"There are times obviously when they are in one-on-ones and they're just going to have to fend for themselves and I thought they did that real well," Longmire said.

"They were outstanding in competing in one-on-ones, our back six."

The Crows took just three marks inside 50 after quarter-time. Kurt Tippett has taken 41 marks inside 50 this season yet took none against the Swans.

Taylor Walker took four marks inside forward 50 yet kicked one goal, three behinds from set shots.

The Swans' Sam Reid, Adam Goodes and Mitch Morton had five set shots for five goals.

That was important because once the mark is taken, the difference between winning and losing can be as simple as the ability to convert those opportunities.

The Crows had one more scoring shot than the Swans. The Cats had just one fewer than Fremantle.

Fremantle's Matthew Pavlich took three contested and three uncontested marks inside forward 50 at Geelong, but from four set shots at goal in the first quarter, he kicked three goals and one out on the full. Those three goals set up the game.

Collingwood seems to have a conundrum, caught in the middle of going long or lowering the eyes.

Trust Travis Cloke deep or look to use the small lead up forwards high?

While five of Cloke's six marks inside 50 on Friday night were contested, all his marks in the forward arc came in the second half.

As the midfield followed long kicks in early on, the Hawks managed to swoop on the ground ball and find a running outlier in space to move it quickly into a vacant forward 50.

That meant Collingwood's defenders were being separated whereas Hawthorn's backs were like an accordion coming together and moving apart with monotonous regularity.

This can't happen against a tall Eagles' attack.

The response required from Adelaide and Collingwood might not be that complicated though. Basic is best, as Longmire knows.

"No secrets at playing this time of the year; [it's] fierce at the footy all over the ground," Longmire said.

Stats supplied by Champion Data