Explained: The DLS Method Sparking Chaos at T20 WC – What It Is & How It Works

Rain has been the only consistent phenomenon at the T20 World Cup 2022, accompanied by the dreaded DLS method,

T20 World Cup 2022: Explaining how the 'DLS Method' works

(Photo: IANS/Altered by The Quint)

None of the 12 teams competing in the Super 12 stage of the ICC Men’s T20 World Cup 2022 has been remarkably consistent so far. The semi-finals favourites in India, South Africa, New Zealand and England have all lost at least one fixture.

Instead, the only consistent phenomenon in Australia has been rain.

The unsolicited and unwelcome intruder has sparked chaos in quite a few games, since it is almost always accompanied by another phenomenon – the trinity of Duckworth, Lewis and Stern.

The DLS method has been a raging topic of discussion, with cricket enthusiasts trying to put on their math wizard capes to learn and unlearn how the process works. In this explainer, we will help you do just that.

What Is the DLS Method?

To put it simply, the Duckworth-Lewis-Stern method, commonly known as the DLS method, is a mathematical calculation. The method is used to calculate par scores and revised targets in rain-affected cricket matches.

To put it simply, the Duckworth-Lewis-Stern method, commonly known as the DLS method, is a mathematical calculation. The method is used to calculate par scores and revised targets in rain-affected cricket games.

To understand how DLS came into existence, let us first delve a bit deeper into history – to the pre-DLS era. The advent of ODI cricket saw the inception of the Average Run Rate (ARR) method in cricket. Unlike the DLS method, the ARR calculations were incredibly simple – based on solitarily the run rate.

In rain-affected games, par score and revised targets were calculated according to the run rate of the team batting first. Say, Team A batted first and scored 160 runs. If the match was reduced to 10 overs, Team B would have needed to score 81 runs to win.

The ARR method was replaced by the Most Productive Overs (MPO) method in 1991. According to MPO, the target of the team batting second was calculated not on the basis of the overall run rate of the team that batted first, but according to the specific run rate in the overs where they scored the most runs.

When Did the DLS Method Come Into Existence?

The ARR method was skewed in favour of the team batting second, whereas the MPO method handed the team batting first a substantial advantage. In a famous 1992 Cricket World Cup game, South Africa needed to score 22 runs in 13 deliveries against England when the match was halted due to rain. When the game eventually resumed, the Proteas were asked to score 22 runs in one delivery.

South Africa needed 22 runs in 1 ball in a 1992 World Cup match against England.

(Photo: Twitter)

British statisticians Frank Duckworth and Tony Lewis started collaborating to devise a better mathematical formulation for rain-affected games after that specific game. Officially, the D/L method was first used in a match between Zimbabwe and England on 1 January 1997, and it was adopted as ICC’s calculation method for rain-affected games in 1999.

Australian statistician Steven Stern recognized the need of tweaking the formulation, owing to the ever-changing nature of the game. Subsequently, the method underwent changes in 2015, and is now known as the DLS method.

How Does the DLS Method Work?

Now then, we finally arrive at the most complex juncture of this explainer, which is, understanding how the DLS calculation works.

Both ARR and MPO methods had a common major drawback – they calculated par scores and revised targets solely on the basis of run rate and overs, not taking wickets into consideration. DLS method, on the contrary, includes both overs left and wickets remaining in the calculation.

The basic principle of the calculation is – Resource. Every team is allocated two sets of resources, that is, wickets and overs. However, these resources are not calculated in their holistic, integer form – they are converted into percentages according to their specific weightage.

Let us simplify things for you with an example – the India vs Bangladesh match at the ICC Men’s T20 World Cup 2022. India batted first and scored 185/6 in their allotted 20 overs.

When Bangladesh came out to bat, they had both 20 overs to face, and all 10 wickets in hand, which translates to 100% of their available resources. With every delivery and every wicket, a team’s resource gets depleted, and accordingly, the par score is calculated.

The match was interrupted by rain after seven overs, when Bangladesh were batting at 66/0.

The formula used in calculating par score according to the DLS method looks like this:

Bangladesh’s Par Score = India’s Final Score * (Resources Utilised by Bangladesh ÷ Resources Utilised by India)

Since India batted first and had no interruptions to deal with, resources utilised by India would be 100%, making the equation look like this:

Bangladesh’s Par Score = India’s Final Score * Resources Utilised By Bangladesh

Given below is the official DLS over-by-over par scores table for the India vs Bangladesh fixture.

Table of over-by-over DLS par scores for India vs Bangladesh match.

(Photo: Twitter/melindafarrell)

According to the DLS calculation, when Bangladesh were 66/0 after seven overs, they utilised about 27% of their available resources. So the calculation would have been: Bangladesh’s par score = 184 * 27% (approx), which comes to around 49.

The loss of wickets is directly proportional to the loss of resources. Hence, had Bangladesh lost four wickets in the first seven overs, the par score would then have been 74.

Importantly, it should also be understood that matching the DLS par score would only mean the scores are tied – the team batting second needs to score an extra run to confirm victory. South Africa’s Mark Boucher had once failed to comprehend this during a 2003 World Cup game against Sri Lanka, which resulted in his team drawing the match instead of what should have been a comfortable victory.

In occasions where a game resumes after an interruption, like the one between India and Bangladesh, the revised target of the team batting second is proportional to the resources depleted from that team’s arsenal.

Can Everyone Calculate DLS Par Scores?

Now that the formula is known, could you start calculating DLS par scores? We are afraid, the answer is no. The resources, as we have mentioned, are not calculated in their integer form, but are assigned a percentage instead according to their weightage. The particular weightage of a single delivery, or a single wicket, cannot be calculated by an individual.

Simply put, the software calculates the ‘resources available’ and ‘resources utilised’ by a team, and according to that, par scores and revised targets are determined. This information is not available to the public.

The complex calculation is done by a software that uses a database of historical scoring patterns from ODI and T20I matches of the past four years. The data of a year’s matches get incorporated into the DLS database on 1 July every year, so as to not make the system redundant in the face of the evolving nature of cricket.

Are There Any Drawbacks to the DLS Method?

While the DLS method is more ‘unbiased’ than its predecessors, it still has its drawbacks. The method came into existence before the inception of T20I cricket. While the process has gone through a few changes, the database still is an aggregate of ODI and T20I scoring patterns, and the resource weightage is much different in both formats. Ideally, the calculation process should be based on format-specific databases.