You either believe in premiership windows or you don't. 

Whatever your belief, only two teams won on Grand Final day in the past decade when their average age was younger than 25 years – and just one of those averaged fewer than 100 games.

Luke Beveridge's Western Bulldogs of 2016 were an anomaly in every sense of the word, coming from seventh and winning four finals to claim a fairytale flag.

The average player in the Bulldogs' team was aged 24.4 years and had a meagre 82.1 matches' experience.

On the flipside, the numbers for seven of the past 10 premiers were north of 26 years and 120 games per footballer.

Crystal-ball gazing ahead of each season is a largely impossible task but history at least provides a solid platform to predict what could happen. 

AFL.com.au has selected a mock 'best 25' for each club – not for round one but factoring in all players who aren't already out for the season – to work out where they are placed in this regard.

The age and experience for those players at every team, as of March 1 this year, were then divided by 25 to reveal their side's numbers.

Where this is flawed is the 'best 25' process is subjective and each individual will have a different view, against the objectiveness of the statistics, but it at least provides a gauge.

Interestingly, only Geelong, Hawthorn and West Coast clear both the 26 and 120 bars at this stage, with Collingwood and Richmond just shy.

Those two clubs should reach the criteria by Grand Final day, with 23 rounds and finals spread across seven months still to go.

For example, the respective numbers for the Tigers' round one team last year were 25.9 and 111.2 and their Grand Final side, as above, was 26.5 and 125.6.

 
The same projection is much harder but somewhat possible when trying to figure out which teams will emerge as this year's finalists. 

Geelong, Brisbane, Richmond, Collingwood, West Coast, Greater Western Sydney, Western Bulldogs and Essendon made the top eight in 2019.

The numbers for their round one side last year were: Cats (25.6/101.5), Lions (25.1/92.5), Tigers (25.9/111.2), Magpies (26/107.5), Eagles (25.2/93.3), Giants (25.7/89.4), Bulldogs (24.3/71.7) and Bombers (25.7/85.2).

Beveridge's Dogs are again the exception, while Adelaide, Hawthorn, North Melbourne, Port Adelaide and Sydney missed out despite fielding sides older than 25 on average in their season-openers.

Conversely, the other bottom-10 clubs last year – Carlton, Fremantle, Gold Coast, Melbourne and St Kilda – all fielded teams younger than 25 on average in round one.

Nothing is certain but, on this measure, the Crows, Dockers, Saints, Suns and Swans might face an uphill battle to qualify for September.

Then again, remember the Bulldogs.

HAWTHORN BEST 22 (according to afl.com.au article)
B: Ben Stratton (31/188), James Frawley (31/225), Blake Hardwick (23/66)
HB: James Sicily (25/82), Ben McEvoy (30/206), Jarman Impey (24/116)
C: Isaac Smith (31/200), Tom Mitchell (26/111), Tom Scully (28/173)
HF: Chad Wingard (26/161), Mitch Lewis (21/14), Jack Gunston (28/192)
F: Paul Puopolo (32/190), Jon Patton (26/89), Luke Breust (29/207)
Foll: Jon Ceglar (29/76), James Worpel (21/33), Jaeger O'Meara (26/92)
I/C: Liam Shiels (28/205), Sam Frost (26/91), Ricky Henderson (31/152), Shaun Burgoyne (37/376)

Next three: Jack Scrimshaw (21/14), Tim O'Brien (25/62), Ollie Hanrahan (21/9)

AVERAGE AGE: 27.04 AVERAGE GAMES: 133.2