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AFL season preview: The knowns and unknowns of the 2020 season

By Cody Atkinson and Sean Lawson


March 19, 2020 08:17:29

Making early season predictions can make a person look silly at the best of times, but it seems to be an especially quixotic pursuit this year.

Until late on Wednesday, we didn’t even know if the opening round would go ahead.

The AFL is hopeful of completing a shortened 17-round season. Will that happen? Who knows. We’re not epidemiologists.

But conjecture and debate are part of what makes sport fun. So, let’s pretend for a moment that everything will go to plan from here.

The season on paper

Over the past few years, we have developed a ladder prediction model at that has proven itself to be about as accurate as any going around.

Like all predictive models, it’s not perfect. The model identifies how teams performed against expectations last year, using a formula developed by the father of modern sports analytics Bill James. It adjusts for strength of schedule and list quality.

James’s formula is called Pythagorean Expectation, and it roughly estimates how many games a team “should” have won based on the points it scored and conceded. The strength of schedule adjusts the performance of sides that had an unfairly hard or soft draw.

The final adjustment is for list quality, which is determined by using the player-rating measure called Player Approximate Value (PAV).

This accounts for list changes from trades and retirements and models the number of games played by each player. We can then work out an expected win total for each team.

So what does the computer say?

As might be expected, 2019’s form sides Geelong and Richmond sit near the top. Although the Tigers’ home-and-away record flattered them a little according to Pythagorean Expectation, the premiership-winning quality of their playing list raises them back up.

Geelong’s dominance on the field is tempered slightly by the loss of Tim Kelly, but it should remain firmly be in the mix in 2020.

Last year’s beaten grand finalist, Greater Western Sydney, is slightly stung by continued player turnover. The bottom half of the Giants’ list is largely unproven, which could be a big factor in an unpredictable season. Similarly, the Adelaide Crows’ depth looks likely to be tested.

Last year’s surprise packet, the Brisbane Lions, could slide a little this year. The player model expects their stellar injury record over the last two years to revert to the mean, while their 3-1 record in close games also suggests they might have slightly overachieved last year.

Generally, games decided by less than two goals are considered toss-ups and the results tend not to be sustainable.

The two sides predicted to climb into the eight are Port Adelaide and Hawthorn. The Hawks could be significantly better.

They played like a side about a win-and-a-half better than their ladder position in 2019, as they navigated a tough fixture. The return of Brownlow medallist Tom Mitchell, the arrival of Jonathon Patton and continued emergence of James Worpel should see their list rating continue to improve.

Not much is expected to separate the sides outside of the top four, with Melbourne in 14th only a couple of predicted wins from eighth. The shortened season will give teams less time to consolidate their ladder position and should see the closest race for the finals in recent memory.

What about our side’s new coach?

After years of stasis, five clubs this year will be hanging their hopes on new men in charge. But does a new senior coach really help a club change its fortunes?

Sort of.

Across the last 24 senior coaching changes since 2010, teams improved their win-loss records by about 5 per cent (from 38.5 per cent to 43.2 per cent) in the year immediately following the new appointment.

The biggest leap in this time was the Crows’ surge after swapping Neil Craig for Brenton Sanderson at the end of the 2011 season when they improved from seven wins to 14 the next year.

In all, 35 per cent of clubs that missed finals the year before they changed coaches made the eight the following year, suggesting that one or two of the new senior coaches in charge may see finals footy this year.

And home ground advantage?

Home ground advantage is another big unknown this season. All games will be played behind closed doors for the foreseeable future.

Whereas home teams are ordinarily thought to gain between a one-point to two-goal advantage at home, the effect on that advantage without crowds is unpredictable.

Across the history of the AFL-VFL, between 56 per cent and 60 per cent of games have been won by the home side.

Last year, 57.6 per cent were won by the home team, which represents a significant advantage. It was even evident in games between teams that share the same venue.

There are a few schools of thought about why home ground advantage exists. Most analysts suggest that crowd noise, and the subsequent impact on players and officials, is the biggest factor.

The book Footballistics found that home sides earned around two extra free kicks per game, which equated to about four points a game. This is largely in line with research in other sports.

However, other factors are also in play, such as the impact of travel on player performance and ground familiarity.

The extraordinary circumstances of the 2020 season may be the perfect experiment to discover the true value of the home crowd.











First posted

March 19, 2020 07:52:39

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