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The Roar



Trent Barrett, the Bulldogs and rugby league’s version of xG: When is a scoring chance a chance?

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21st March, 2022
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On Sunday night, Canterbury managed to get 59 per cent of the possession, spend most of that in Brisbane’s half, win the offload count 20-2, and run for 600 more metres than their opponents.

Yet they managed to score just two tries, one of them a dummy-half run from close to the line and the other a well-worked move for Matt Dufty to put Braidon Burns over.

It’s not a great return on investment to get ten points from an overwhelming ball and field position advantage, which was my question to Trent Barrett in the media conference.

It would be safe to say he didn’t agree with that assessment.

“I think you’ve got it wrong there,” he replied. “We created a lot of chances and if you go back and look at it, we got over the line four times in the first half.

“They created a lot of chances in the second half, but we haven’t got the polish there to convert them. That’s something that we have to keep working on.

“I’m on with that, but if you look at it, we probably created eight tries but only came away with a couple.”

The question wasn’t so much whether the Dogs created chances, but more about the quality of the ones they created. That’s where my interpretation and Barrett’s diverged.

There’s no metric for measuring how good a chance for a try was, so there are no hard numbers to go on here, but it’s an idea worth thinking about.


So what constitutes a good scoring opportunity? In football, they have a clear stat for this: expected goals (xG).

If you don’t like football, by the way, keep reading, because this will get back to the Bulldogs and this concept is put forward to make a point about them and Barrett.

To overly simplify things, xG uses historical data about the location on the field from which a shot was taken, impacted by the type of shot (a header, for example, is weighted different to a static ball) and how many defenders were in between the shot location and the goal, to generate a probability that a shot would have resulted in a goal.

A penalty kick, for example, might get an xG of around 0.76 because penalties are scored around 76 per cent of the time, while a shot from the halfway line might get a 0.01 as that’s a very low probability shot to take.

If you work out the xG per shot for each team and then add them together over the course of a match, you get a decent idea of who – performance-wise at least – should have won based on the quality of chances created.

As with all stats, there are limitations: xG can’t factor in, for example, a good chance that doesn’t result in a shot – a pass that flashes across goal but is never touched by an attacker – nor double-count shots that are saved and then result in a second shot from the rebound, a rebound that otherwise would not have occurred had the first shot gone in.

But in general, it is as good a way as we have of understanding the flow of a game that goes beyond the nuts and bolts of the scoreline.

In a rugby league context, there is no equivalent way to rank chances. One blogger, The Rugby League Eye Test, was maintaining such a stat, xPoints, that sought to quantify how well a team playing by weight of field position and possession combined.

You can read the full explainer here, but this is the short of it: split the field up into 450 sections of 4x4m square and use historical data to work out the potential for various events when the ball was in each section, whether tries, penalties or field goals.

Obviously, the closer the section was to the opponent’s line, the more likely it was that a play starting there would result in a try, because most tries are scored from closer in, and the closer it was to the centre, the higher the likelihood of a try, because it is easier to defend one side at a time than both sides.


The limitation of xPoints is that lots of tries are scored from further out – Manly and Melbourne, for example, were experts in this last year – and some teams actively preferred to defend their line rather than other areas, because all they have to do is fire out and make the tackles.

The Roosters are goal-line defensive experts and not at all fussed to tackle from there, while in Super League, it is not uncommon to see a team carry an attacker over the line and hold them up to force them to go back to the 10 metres rather than get the play the ball a metre out, because some teams think that distance is optimal for goal-line defence.

It’s not a perfect stat – and indeed, no perfect stats exist – but it is useful for working out who got enough field position to score, and conversely, who should have scored more with the field position that they had. Weight of possession in the right areas equals tries more often than not.

The not is Canterbury. Mr Rugby League Eye Test himself told me that he had thought there was a data error when devising the xPoints stat when it produced such a high score for the 2021 Bulldogs.

In fact, it was just that they got into good positions quite a lot but failed to score, as evidenced by having the best completion rate in the league last time around but by far the fewest tries.

This brings us back to Sunday night at Accor Stadium, and why Barrett’s remarks were off the mark. His team didn’t create chances, they merely created the field position for chances to occur.

Matt Burton had one dart that was a try-scoring chance created, denied by an excellent tackle from Kotoni Staggs that prevented a grounding.

Matt Burton of the Bulldogs

Matt Burton of the Bulldogs (Photo by Ian Hitchcock/Getty Images)


Other than that though, the Dogs certainly had a lot of ball, and a lot of field position, but never really asked the requisite questions of the defence.

They did get over the line, but in such a manner that it wasn’t likely that they’d score: kicks in behind that went dead and players held up in-goal trying to barge their way over.

There were two main problems that caused this problem to occur. Jake Averillo is not a halfback, he’s a running five-eighth and the Dogs already have a better one of them in Burton, as well as a running fullback in Matt Dufty, so they really don’t need another guy who can do the same thing.

Averillo ran 17 times in 80 minutes, which is not a good statistic for a halfback. Too many runners spoil the broth, as it were, because the defence doesn’t have to deal with the idea of a pass or a kick when they know the first option of all three major playmakers is to go themselves.

This isn’t to put a bat signal up for Kyle Flanagan (yet) but having someone who is an organiser, kicker and distributor, even if they’re not that good at it, might be a better idea when you know that your other two playmakers are always going to run.

In the NSW Cup game that proceeded the Dogs vs Broncos fixture, the reserves won 48-12 against a strong Canberra, with Flanagan picking up two try assists and generally steering the side around.

The second issue is that drastic imbalance between the two sides of the field means that the Dogs are very, very predictable.


Consider the two sides of the field and where the Dogs have put their investment. On the left, you get Josh Addo-Carr, Brent Naden and Burton, which is a fairly serviceable NRL edge.

On the right, you get Jayden Okunbor, Braidon Burns and Averillo.

Jayden Okunbor of the Bulldogs looks on

Jayden Okunbor (Photo by Ian Hitchcock/Getty Images)

If you need to score with the game on the line, which way are you going to pass the ball? It’s not going to be the one that ends up with it in the hands of Okunbor. Brisbane knew this too, so they had a good handle on how the Dogs would attack.

There are a few ways around this problem for Barrett. He could put Flanagan in (or another actual halfback), which would allow Averillo to play in the centres and run all he likes.

He could put any one of Aaron Schoupp, Declan Casey, Isaac Lumelume or even Burns onto a wing to defend a lot better than the current incumbent while offering the same if not more in attack.

But all of these require him to think there is actually a problem in the first place. If he still thinks that his team created enough chances to win that game on Sunday night, maybe nothing can help him.

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