DECIDING to undergo a list rebuild is like booking in for surgery: the pain comes well after making the call to go under the knife.

Clubs towards the bottom of the ladder this season, in particular North Melbourne, Adelaide and Hawthorn, are prime examples of list regenerations that do not happen overnight.

And the data shows how list demographics take time to adjust and then transform.

In 2019, Hawthorn ranked as the oldest average age per team in the AFL at 26.5 years, with Adelaide second at 26.4. West Coast, fresh off its 2018 premiership win, was equal third-oldest at 26.2, with North Melbourne also ranked at the same level.

But three years on, list cuts at the Crows, Hawks and Kangaroos have entered the upside down: after 18 rounds this season, Adelaide remains clearly the youngest side in the competition for average age (24 years), with Essendon and North Melbourne equal second-youngest at 24.6 years and Hawthorn next youngest at 24.7.

The Crows have won one of their past five games – their five-point defeat to Collingwood last week was one of their best showings of the second half of their season – but are now deep into their rebuild after they made aggressive list changes following their 2017 Grand Final defeat.

The rebuild is vexed: it doesn't happen straight away, but neither does the bottoming out, as seen in the age variation from the Crows in 2019, which was the first year after Adelaide had begun to overturn its group.

As North Melbourne discusses priority pick options with the AFL after winning 19 of its past 78 games, the Crows have won 25 games in the same period, showing the patience required with longer plans.

The other complication for teams that had commenced their rebuild around 2019 is the unforeseen 2020 disruptions, where recently drafted players were robbed of vital state league opportunities to develop and that year's draft – identified as a key one for several clubs – was compromised due to the lack of games played by prospects.

Some other notable takeouts from the list demographics data show the Eagles to have remained the third-oldest team on average each week, three years after they were at the same level in 2019, while the maturation of Brisbane from growing group into flag contender is seen in the ages too, with the Lions going from 11th-oldest team in 2019 to fourth-oldest this year.

St Kilda, too, was second-youngest in 2019 and is now fifth-oldest on average.

2022 average age per team (youngest to oldest)
Adelaide – 24 years
Essendon – 24.6
North Melbourne – 24.6
Hawthorn – 24.7
Carlton – 24.8
Fremantle – 25.1
Gold Coast – 25.1
Melbourne – 25.3
Sydney – 25.3
GWS – 25.5
Western Bulldogs – 25.5
Port Adelaide – 25.7
Collingwood – 25.8
St Kilda – 25.8
Brisbane – 26.1
West Coast – 26.1
Richmond – 26.8
Geelong – 27.7

2019 average age per team (youngest to oldest)
Gold Coast – 24 years
St Kilda – 24.4
Sydney – 24.4
Western Bulldogs – 24.4
Carlton – 24.6
Fremantle – 24.8
Melbourne – 24.8
Brisbane – 25.2
Port Adelaide – 25.2
Richmond – 25.2
Essendon – 25.3
GWS – 25.6
North Melbourne – 25.8
Collingwood – 26.2
Geelong – 26.2
West Coast – 26.2
Adelaide – 26.4
Hawthorn – 26.5

* Age of teams is an overall average of the selected senior sides throughout the season