Analysis – Stocky vs Reality: Did your team outperform? (Pt I)

The Stocky is the main forecasting tool driving the analysis on this site. It’s a simulator of the season ahead, using the Monte Carlo method and based on Elo ratings, that gives insight into the future performance of each club. My main interest has been the number of wins, as it determines ladder positions which in turn have a big impact on the finals. The Stocky might not be able to tell you which games a team will win, but it is good at telling you how many wins are ahead.

But how does a computer simulation (in reality, a very large spreadsheet) compare to reality? To test it, I’ve put together a graph of each team’s performance against what the Stocky projected for them. Each graph shows:

  • The Stocky’s projection for total wins (blue)
  • Converting that projection to a “pace” for that point in the season (red)
  • Comparing that to the actual number of wins (yellow)

It will never be exactly right, particularly as you can only ever win whole numbers of games and the Stocky loves a decimal point, but as we’ll see, the Stocky is not too bad at tracking form and projecting that forward.

This week is Part I, from Brisbane to Newcastle. Part II, from North Queensland to Wests Tigers, will be next week.

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NRL Tips – Round 24, 2017

Only three games to go. There are a couple of finals places still up for grabs, as well as the all important wooden spoon battle, which is proving to be more inspirational than wondering which big market team is going to finish where in the top four.

Draw

gold coast titans-sm Gold Coast (7-14) @ parramatta-sm Parramatta (13-8)

While the Gold Coast melts down over whether they’ll keep their coach or their “star” fullback/centre or boot both or neither, Parramatta have had to spend a week of soul searching after a devastating loss to Newcastle – probably the worst side to play this decade – brought their six game winning streak to a grinding halt.

The question is: Will Parramatta recover? I almost think it’s irrelevant what the Eels do. The real question is: do the Titans even bother to show up or will they follow their erstwhile leader’s example and half ass it? I’m expecting three-quarter ass tops, so the Eels should be able to recover and get their finals campaign on track.

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NRL Tips – Round 23, 2017

It may surprise you to discover that this blog is actually fairly low on my list of priorities and when time’s tight, its always going to be the first to suffer so this isn’t going to be much of a post. With that in mind, this week’s games are looking like a re-run of round 20, where each game had a clear favourite. That weekend, seven from eight tips got up.

Round 23 offers more top eight match ups with the Roosters/Storm, Broncos/Sharks and Cowboys/Panthers going head-to-head. While you would expect 1st vs 2nd, 3rd vs 4th and 6th vs 8th to be tight, we’ve got the Storm, Broncos and Panthers well ahead of their rivals. In fact, the Jury was unanimous on every game except for Wests/Manly, where Euclid was the sole dissenting vote.

The favourites have an average odds of 2-to-1 of picking up the win. As I warned in round 20, you would expect to be correct in 5.2 games but still find upsets in 2.8 games. We’ll have to wait and see which games those are.

Draw

canterbury-sm Canterbury (7-13) @ souths-sm South Sydney (7-13)

newcastle-sm Newcastle (4-16) @ parramatta-sm Parramatta (13-7)

cronulla-sm Cronulla (13-7) @ brisbane-sm Brisbane (13-7)

gold coast titans-sm Gold Coast (7-13) @ st george illawarra-sm St George Illawarra (10-10)

sydney city-sm Sydney City (14-6) @ melbourne-sm Melbourne (15-5)

north qld-sm North Queensland (12-8) @ penrith-sm Penrith (11-9)

canberra-sm Canberra (9-11) @ warriors-sm New Zealand (7-13)

manly-sm Manly (12-8) @ wests tigers-sm Wests Tigers (5-15)

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Analysis – The more competitive the season, the more bums on seats

Most rugby league commentators wouldn’t know what a linear regression is or how do one. I’m no different but I do like to compare two variables and see if they’re correlated. A scatter plot with a linear trendline and an R-squared – remember R-squared goes from 0, no correlation, to 1, perfect correlation; I usually need at least 0.2 to raise an eyebrow – is all I need to keep me entertained for hours on end.

Last week, we looked the concept of competitiveness and how to measure it. This week, I want to see if (more or less) competitiveness impacts on other aspects of the game. Using my preferred ratings gap as a proxy for how competitive a season is, this post looks at a few variables to see if they’re correlated.

If you want a specific variable looked at, give me a yell.

Draws

draws vs gap

Surprisingly, there’s no link between the number of draws and how competitive the season is. There’s basically a correlation of nothing with an R-squared of 0.03 . I think draws are more about the specific teams in question and I think golden point may play a role but the overall season competitiveness doesn’t matter.

As an aside, it appears that the number of draws are increasing over time. I’ve looked into it and basically, that’s not a thing. Yet. 2016 was a particularly bad year and maybe if 2017 continues on trend, then we may be able to establish there’s something happening but we’ll have to wait and see.

Points scored

points vs gap

I had to adjust it for point scored across the season per regular season game but there’s no correlation between competitiveness and points scored. They’re independent of each other.

Attendance

attendance vs gap

Look, I’ve know I’ve gone on about attendance this year, but this is interesting. Promise. The more competitive the season, the more people turn up. This relationship holds even if you remove an outlier year like 1998, which had really poor attendance due to an excess of games and it immediately followed the Super League shemozzle.

It folds in nicely to some work done by Tony Corke for the AFL. We see that people prefer to attend games where there’s a bit of uncertainty. If it’s expected to be a lopsided flogging, people stay home compared to when there’s a chance of it going either way, i.e. when its competitive.

If the NRL wants more bums on seats, all it has to do is tighten up the competition. Introducing a spending cap on performance would go a long way to evening it up.

NRL Tips – Round 22, 2017

I struggled to get this post together. I must be running low on creative juices after what feels like a season that’s already been decided (Melbourne to win everything) but for some reason, we have to go through the formalities of playing the last few games. I propose we just lock the ladder positions now, go to the finals and wrap up a month early. Just in case the NRL isn’t listening to the fifteenth best non-podcast/non-gambling based blog, here’s how I think the round will go.

Draw

parramatta-sm Parramatta (12-7) @ canterbury-sm Canterbury (7-12)

Tuesday’s front page of the Daily Telegraph means we all need to sympathise with Bulldogs fans as they get painted with the same brush as an alleged terrorist, a sentence you would never write in any other sport. It’s okay though because by the weekend, we’ll all be back to panning the Bulldogs’ terrible on-field performances.

Parramatta beat the Broncos last week, taking their streak to four wins on the trot. What utter bastards. Having been forced to watch Eels’ games lately, I’m not entirely convinced they’re the real deal, particularly defensively. That won’t matter this match because the Bulldogs are pathologically incapable of scoring points (and we’re back, baby). Parra will be able to run in the minimum fourteen points required and so the Eels will win.

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Analysis – Is the NRL getting more competitive?

The short answer is yes and no. Yes, the NRL is more competitive now than when it started but no, it doesn’t seem to be a thing that improves consistently year-on-year.

Let me explain. On this blog, we use Elo ratings to measure teams’ performances and assess each team’s probability of winning a game in advance. Surely we can use our ratings system to assess the competitiveness of each NRL season.

Philosophically, what is a high level of competitiveness? It has to be a situation where the teams are fairly close in performance resulting in a hard to predict outcome. Here’s two ways of measuring that closeness of performance with pros and cons.

  1. You could look at the spread of teams ratings. Pro – makes an assessment based on all teams. Con – if all teams are pretty average but one team is excellent and another awful, then there isn’t a big spread of talent. This would imply a highly competitive season even though there is really only one potential premiership contender.
  2. You could look at the difference between top and bottom ratings. Pro – simple. Con – if one team is truly terrible and three or four are pretty good, then the season is pretty competitive but the difference between top and bottom might be exaggerated due to the crapiness of the bottom team. This would imply a not particularly competitive season despite there being multiple potential champions.

Which is better, measuring the spread or measuring the difference from top to bottom? Neither way of doing this is immediately obvious as a better method. Let’s look in more detail.

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Analysis – Your team and their finals appearances

There was a remark on Twitter a while back that Mitchell Moses had left Wests because he wanted to play finals footy but had chosen to go to the only club that had been without a final appearance longer than the Tigers. That didn’t seem right but I looked into it and it was true.

That got me thinking. How often do teams turn up to the finals? Some, like the Storm and Cowboys, seem to be regular fixtures but how do the rest fare?

Warning: this is going to be one of those “Well, yeah, I knew that” type posts. This is not about showing off some fancy analysis, just a bit of curiosity.

Double warning: Pie charts ahead.

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