Previous article can be found here We all love a good debate over a few beers. Or chardonnays, if you are an Eagles supporter (like me).

To read this column and get full banter benefit, I’d ask you to keep a couple of things in mind.

1. Statistical models by definition are an abstraction from reality and numbers can only tell part of the story…the rest of the story is yours to tell.

2. If you end up reading this in Sydney, feel free to seek me out and buy me a beer (I will not say no to AFL/stats talk + beer)

This weeks’ debate to be had over beers and possibly tears: does defence really win premierships?

It is a common theme and has been talked about on some great AFL statistics blogs, including my personal favorite.

We all love a good debate over a few beers. Or chardonnays, if you are an Eagles supporter (like me).

To read this column and get full banter benefit, I’d ask you to keep a couple of things in mind.

1. Statistical models by definition are an abstraction from reality and numbers can only tell part of the story…the rest of the story is yours to tell.

2. If you end up reading this in Sydney, feel free to seek me out and buy me a beer (I will not say no to AFL/stats talk + beer) Related Content

This weeks’ debate to be had over beers and possibly tears: does defence really win premierships?

It is a common theme and has been talked about on some great AFL statistics blogs, including my personal favorite.

If we did a simple Elo rating for offence and defence in the AFL, my model would work as follows: say we have West Coast playing the Hawks at Subiaco, the Eagles’ predicted score is the average home score (of all AFL teams) plus the Eagles’ attack rating, minus the Hawks’ defensive rating. The Hawks’ predicted score would be the average score (of away teams) plus their away offensive rating minus the Eagles’ defense rating.

Putting that model into action and the numbers paint a really interesting picture of the 2015 season.

We can see the Dockers start off the year in amazing form but after round nine their defence levels out and their attack rating goes down and fast!

The Eagles, start out the year relatively stable but then go on a great run of form from round five onwards.

The Hawks, grand final victors, play at an incredible high level throughout but really kick things off from round 15.

The Bulldogs, while steady throughout the earlier part of the year make a late spectacular run and and the Kangaroos are another side to surge late. On the other hand Port Adelaide, a team lots of footy fans love to see play, declines from an initial high rating from a spectacular 2014 season.

Looking at the team’s average defensive ratings, we can see that in terms of making the preliminary final, there is some separation between the preliminary finalists (marked in blue) and the rest of the pack (the Roos are a slight anomaly here).

But the usefulness of defensive ratings gets really interesting when it comes to assessing the grand final. Check out the following GIF (premiership winners marked in blue):

The two 2010 grand finals throw up a quirk but you can see that the team with the highest defensive rating doesn’t win the decider - except for the Sydney Swans in 2012.

Interestingly the Swans’ attack rating minus the Hawks’ defence rating was actually positive. That Sydney side was great defensively but not too shabby offensively either (and had a higher overall rating playing away than it did at home).

So does defence win premierships? By the numbers you’d have to suggest not.

Defence might help you get to the big dance (or very close to it) but to take home the flag you definitely need some offensive firepower.

That seems a good poser for Fremantle fans to ponder as the 2016 season rolls on, given how defensively-focused the Dockers have become in Ross Lyon’s time in charge.