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.

Continue reading “Analysis – Stocky vs Reality: Did your team outperform? (Pt I)”

NRL Projections Update – Round 23, 2017

Results

souths-sm South Sydney 28 (8-13) d canterbury-sm Canterbury 14 (7-14)

newcastle-sm Newcastle 29 (5-16) d parramatta-sm Parramatta 10 (13-8)

brisbane-sm Brisbane 32 (14-7) d cronulla-sm Cronulla 10 (13-8)

st george illawarra-sm St George Illawarra 42 (11-10) d gold coast titans-sm Gold Coast 16 (7-14)

melbourne-sm Melbourne 16 (16-5) d sydney city-sm Sydney City 13 (14-7)

penrith-sm Penrith 24 (12-9) d north qld-sm North Queensland 16 (12-9)

canberra-sm Canberra 36 (10-11) d warriors-sm New Zealand 16 (7-14)

wests tigers-sm Wests Tigers 30 (6-15) d manly-sm Manly 26 (12-9)

Collated Ladder

Now to look ahead to see what the Collated Ladder has predicted for the final standings of the season.

Melbourne are currently sitting on sixteen wins and are projected to take eighteen. With three games to go and playing very well, that might be more like nineteen by the end of the regular season. Brisbane and Sydney City close out the top three spots, just as they do now. Both sides are going to stay at least four points off the pace.

The remaining spots are interesting. Penrith in the top four? They’re currently only two points off Cronulla, who are not playing well. Three wins for the Panthers and two for the Sharks would not be a surprising outcome. The Collated Ladder also has the Cowboys not far off the pace and there’s not much to separate them – Stocky wins and Pythag are very close for all three. Fourth place is very important as almost all of the premiership winners of the last twenty years have finished in the top four.

Continue reading “NRL Projections Update – Round 23, 2017”

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 Projections Update – Round 22, 2017

I’m running a bit short on time this week, so I’ll dispense with the usual round up of matches and dive straight into it.

Actually, I’ll take one moment to say that I watched five of the eight games on the weekend (missed the Saturday fixtures) and the Souths-Saints game was the best of the lot. It might be because my expectations were so low but that was a hell of a finish from the Bunnies.

Round 22 Results

parramatta-sm Parramatta 20 (13-7) d canterbury-sm Canterbury 4 (7-13)

souths-sm South Sydney 26 (7-13) d st george illawarra-sm St George Illawarra 24 (10-10)

melbourne-sm Melbourne 26 (15-5) d north qld-sm North Queensland 8 (12-8)

newcastle-sm Newcastle 26 (4-16) d warriors-sm New Zealand 10 (7-13)

brisbane-sm Brisbane 54 (13-7) d gold coast titans-sm Gold Coast 0 (7-13)

canberra-sm Canberra 30 (9-11) d cronulla-sm Cronulla 12 (13-7)

manly-sm Manly 36 (12-8) d sydney city-sm Sydney City 18 (14-6)

penrith-sm Penrith 28 (11-9) d wests tigers-sm Wests Tigers 14 (5-15)

Continue reading “NRL Projections Update – Round 22, 2017”

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.

Continue reading “Analysis – Is the NRL getting more competitive?”

NRL Projections Update – Round 21, 2017

I think rugby league historians prefer the expression “dour” when they really mean “boring” game. The Panthers-Bulldogs match on Thursday night will not be making much of an impression in the record books and so I think we’re safe to use the expression “boring”. The teams went to the break at Pepper Stadium even but we all knew something from the Panthers was coming and they delivered, scoring two more tries and taking the win.

The Sharks were never in any real doubt against the Warriors in Auckland on Friday night. The Warriors out-errored the league leaders in the field and lost out in possession, the kicking game and the game overall to the Sharks. The Broncos were in the picture in the first half against the Eels, sprinting out to a twelve point lead in the first ten minutes. The Eels got level quickly and kept the Broncos’ playmakers quiet and out-muscled their forward pack. Jonus Pearson was a liability on the Brisbane wing, slipping over half a dozen times, while Corey Norman and Mitchell Moses have formed a solid combo in the Eels’ halves, steering Parramatta to a win.

After dismantling Manly the week before, the question was “Are St George good again?” The answer was a resounding “no”. Everything went the Knights’ way for a change in front of a good turnout in Newcastle. With only a narrow lead at half time, the expectation was that the Knights would fade away but they kept the Dragons out and sealed the win with a late try and field goal. Taking a 3-1 try lead into the break, Canberra were in control of their rendezvous with Souths. The Raiders eventually took the win after the full eighty, despite a late consolation try for the Bunnies, avoiding the need for the childish meltdowns that has marked more recent Canberra losses. At Allianz, the Cowboys stormed to an early lead and looked in pole position to take a somewhat surprising win. The Roosters showed why they are in contention for this year’s minor premiership and overall premiership by pegging the Cows back to even and then taking the lead by the three-quarter mark. The Roosters kept the Cowboys at bay for the remaining quarter of the tense affair to take the two points.

Melbourne demolished Manly on Sunday afternoon for Cameron Smiths’ 350th game. The Sea Eagles were only down by six at half time before the Storm monstered their way through the second half to take a commanding win. Manly have now suffered two big losses in a row, raising questions over their form. On the Gold Coast, the Titans basically handed the Tigers a win on a platter. Any time the Gold Coast looked dangerous or in a scoring position, they managed to drop the ball or pass it forward. Wests’ execution was cleaner and netted them two points in an otherwise unentertaining game.

Round 21 Results

penrith-sm Penrith 16 (10-9) d canterbury-sm Canterbury 8 (7-12)

cronulla-sm Cronulla 26 (13-6) d warriors-sm New Zealand 12 (7-12)

parramatta-sm Parramatta 28 (12-7) d brisbane-sm Brisbane 14 (12-7)

newcastle-sm Newcastle 21 (3-16) d st george illawarra-sm St George Illawarra 14 (10-9)

canberra-sm Canberra 32 (8-11) d souths-sm South Sydney 18 (6-13)

sydney city-sm Sydney City 22 (14-5) d north qld-sm North Queensland 16 (12-7)

melbourne-sm Melbourne 40 (14-5) d manly-sm Manly 6 (11-8)

wests tigers-sm Wests Tigers 26 (5-14) d gold coast titans-sm Gold Coast 4 (7-12)

Continue reading “NRL Projections Update – Round 21, 2017”

NRL Projections Update – Round 20, 2017

The Broncos kicked off round 20 by throttling the Bulldogs. Brisbane were on from the gun and Canterbury were in the contest for the first twenty minutes before conceding late tries before half time. The Broncos returned after the break firing and after securing a series of repeat sets in the third quarter, ran the Bulldogs to exhaustion and piled on the points.

The Knights are almost not worth commenting on anymore. One try came in the thirtieth minute for Newcastle but otherwise it was one-way traffic to Bondi. The Roosters accumulated tries throughout the game to run out comfortable winners. Souths were never in the contest against Cronulla. There was a whiff of upset but the Sharks showed up early, used their league-leading defence to keep the error-riddled Rabbitohs at bay and didn’t leave themselves too much work to do, to the delight of the home crowd.

Saturday saw three wins with each going the way they were expected to but with none decided by more than twelve points. The Titan succumbed to the Panthers at Pepper Stadium. Gold Coast had an early lead and went into half time near even but Penrith took control in the second half and took the win. In Canberra, the Raiders reinforced their reputation for crappy discipline with some big, late hits on Storm players. That didn’t stop Melbourne from outplaying the home team but injury concerns for the Storm now hang over their premiership chances. North Queensland played out a scrappy contest with New Zealand in Townsville. The Cowboys made fewer errors and had just enough attacking panache to outpace the Warriors and carry the two points.

In the Tips post, I suggested that despite the massively lopsided nature of this round, a couple of upsets were still on the cards. The Dragons duly obliged by obliterating the Sea Eagles. Manly were down by thirty at half time and nearly managed to drag themselves back into it before Saints re-accelerated and left them behind. At ANZ, a western Sydney derby played out in front of 30,000 people. They were treated to a close contest, albeit one with a significant number of errors. Parramatta just edged out Wests with a field goal in the final ten minutes. The Tigers were unable to respond and sank.

Round 20 Results

brisbane-sm Brisbane 42 (12-6) d canterbury-sm Canterbury 12 (6-12)

sydney city-sm Sydney City 28 (13-5) d newcastle-sm Newcastle 4 (2-16)

cronulla-sm Cronulla 26 (12-6) d souths-sm South Sydney 12 (6-12)

penrith-sm Penrith 24 (9-9) d gold coast titans-sm Gold Coast 16 (7-11)

melbourne-sm Melbourne 20 (14-4) d canberra-sm Canberra 14 (7-11)

north qld-sm North Queensland 24 (12-6) d warriors-sm New Zealand 12 (7-11)

st george illawarra-sm St George Illawarra 52 (10-8) d manly-sm Manly 22 (11-7)

parramatta-sm Parramatta 17 (11-7) d wests tigers-sm Wests Tigers 16 (4-14)

Continue reading “NRL Projections Update – Round 20, 2017”