Author Archives: pythagonrl

A deep dive for each NRL team’s 2018 season

The only thing more reliable than March bringing rugby league back is the slew of season previews that each and every media outlet feels the need to produce. I’m no different in this regard and here is what is likely to be the longest post I’ve ever compiled.

This year’s season preview takes a look at each team and is a mix of my usual statistics, a bit of SWOT analysis and some good old fashioned taking a wild punt and hoping it’ll make you look wise come October.

(A SWOT analysis is where you look at Strengths, Weaknesses, Opportunities and Threats. There’s only one threat in the NRL, and that’s the other fifteen teams, so it’s more of a SWO analysis)

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A Complete History of the NRL (nerd edition)

Last year, I did a report on each NRL club featuring a bit of history, a few statistics and some graphs. The series didn’t do super well in terms of clicks but also didn’t take a lot of effort to produce.

One thing I did enjoy putting together were the class graphs. These use a slow moving Elo rating system called Eratosthenes to track the long term performance of clubs. You can see a full listing of all current ratings here.

If you’ve got the right kind of stuff between your ears (that is, if you’re a massive nerd), each picture tells each team’s thousands of words history in the NRL. To that end, I’ve updated all sixteen clubs’ graphs to the end of the 2017 season for your nerdy consumption.

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Season preview: who has the softest draw?

This headline (the actual article is fine) from Tim Gore typified the attitude when the draw was released in November last year:

time gore headline.PNG

Not only were the NRL never going to redo the draw, it speaks to the tendency that the they can do no right in the fans’ eyes (“Release the draw earlier! No, not that one, a different one”).

Looking at last year’s ladder and having a whinge that your team has to play three top four teams twice is peak gronkery. It’s fuelled by emotion and we can do better. So here you go: a quantitative analysis of who has the toughest draw in the NRL.

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Predicting this year’s NRL premiership winner with class

Can we predict a premiership winner from their Elo ratings?

Embed from Getty Images

Obviously, yes. That’s what the Stocky is for and this site would pointless if this was not true. But what if we wanted to look into the future before a single game has been played? I think that the Elo ratings of premiership winning teams might have a common pattern to them that show up if we take a closer look at their long term performance, or class, ratings with Eratosthenes.

We’ll need some premiership winners to review. To do this analysis I’ve tried to pick one premiership per club (to avoid autocorrelation) and pick a premiership that stands on its own. That eliminated a number of premierships years for Melbourne and multiple premierships for Manly and Brisbane. I also biased it towards more recent premiers where possible. I was left with the following list:

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Primer – StatScore and Win Shares: rating NRL players

If you’d like to skip the explanation and see the full list of StatScores and Win Shares, you can go to this Google Sheet.

The biggest off-season story in the NRL was the transfers of Cooper Cronk from Melbourne to Sydney and then Mitchell Pearce from Sydney to Newcastle. From the Roosters’ perspective, for two players likely on similar pay packets, how did the Roosters decide one was better than the other? Then I wondered if it were possible to work out a way of judging value for money in player trades. It’s big in baseball, so why not rugby league? This led me to develop StatScore and Win Shares as ways to numerically evaluate rugby league players.

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Primer – How do the Indices work?

If you’re wired for numbers, like I am, it can be hard to deal with people’s feelings and understanding why they think the things that they do. That’s why I’ve decided to quantify the feelings a team generates into five distinct indices: Power, Hope, Panic, Fortune and Disappointment.

Each index has two components. There’s a main mechanism for ranking the teams and some minor tie-breaking stats. The main mechanism typically uses Elo ratings to make an estimation of what we expect from a team, whether or not they are meeting that expectation and what that means for the season ahead. The tie-breakers are statistics used to award a few points here and there to help rank the teams should they have similar mechanism results.

Editor’s note: As much of last season’s material was influenced by The Arc, much of this season’s material owes a debt to SB Nation, including the idea of panic/hope indices.

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Primer – Who are the Greeks? 2018 Edition

The Greeks is the collective name given to a series of Elo rating models for tracking performance of rugby league teams and forecasting the outcomes of games. I usually refer to them as if the philosopher himself was making the prediction, even though the Greeks have mostly been dead for a couple thousand years and certainly would never have heard of rugby league or Arpad Elo.

The differences between each Greek are on the subtle side, with the intention of measuring different things. You may want to revisit primers from last year:

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