Explainer: What is the DLS method in cricket which determines revised targets in rain-affected matches?

When a cricket match is affected by rain, then there is a stoppage of play. When play resumes after a couple of hours, the team that is bowling either bowls a reduced number of overs. For the team that is chasing, they are chasing a revised target. The revision brought about by a mathematical calculation known as the DLS method. For decades, the DLS method has made matches interesting, confounded teams and resulted in heartbreak. For the last 20-plus years, the DLS method has determined the result in case of a match being affected by rain, bad light or any other climatic condition.

Just what exactly is the DLS method? How is it calculated? How did it come up in the cricketing world. Here is an explainer.

What is the full-form of DLS method?

The full form of the DLS method is Duckworth Lewis and Stern method. It is been named after mathematicians Frank Duckworth, Tony Lewis and Professor Steven Stern.

Hang on, wasn’t it previously called only DL method?

Yes, this method was initially called the Duckworth Lewis method. However, with the retirement of Duckworth and Lewis, Professor Stern became the custodian of the method and it was renamed in November 2014.

What resulted in the DLS method?

In the 1992 World Cup held in Australia and New Zealand, in order to determine results for rain-affected games, the rain rule method was introduced. In this, the system of The Most Productive Overs method was used. The method took no account of wickets lost by the team batting second, and effectively penalised the team batting second for good bowling by ignoring their best overs in setting the revised target.

When was the system deemed flawed?

The rain-rule was effectively chucked during the farce in the 1992 World Cup clash between England and South Africa in Sydney. Rain stopped play for 12 minutes with South Africa needing 22 runs from 13 balls. The revised target left South Africa needing 21 runs from one ball, a reduction of only one run compared to a reduction of two overs, and a virtually impossible target given that the maximum score from one ball is generally six runs. The outcome of the match saw many analysts say that the rain-rule method had to go.

When was the DL method conceptualised and when was it officially used?

Duckworth and Lewis conceptualised the DL method in 1997 and the ICC officially used it in 1999.

Was the DL method also flawed?

When one looks at the history of the DL method, there were two corrections needed. In 1999, the DL method did not take into account very high scores of the match. Lewis noticed that there was an inherent weakness in the formula that would give a noticeable advantage to the side chasing a total in excess of 350. A correction was initiated but it was not used until 2004.

How is the DL par score calculated?

This is a very complex equation. There are plenty of mathematical formulas involved in this. However, the one basic calculation in the DL score is

Team 2’s par score = Team 1’s score X Team 2’s resources divided by Team 1’s resources

What are the resources?

The resources in this case is the number of overs they have to receive; and the number of wickets they have in hand. For example, if a rain delay means that Team 2 only has 90 percent of resources available, and Team 1 scored 254 with 100 percent of resources available, then 254 × 90 / 100 = 228.6, so Team 2’s target is 229, and the score to tie is 228.

If it is a 50-over match and Team 1 completed its innings uninterrupted, then they had 100 percent resource available to them, so the formula simplifies to:

Team 2’s par score = Team 1’s score X Team 2’s resources

Is there an alternative to the DLS?

Yes, there is the VJD method which was conceptualised by a civil engineer from Kerala, V Jayadevan. This system was used in the 2019 Vijay Hazare Trophy and was also employed in the Tamil Nadu Premier League. The VJD system divides the innings into phases. It assumes a high scoring rate in the first few overs, considering fielding restrictions, assumes a drop in the rate in the middle overs, and assumes another rise in the slog overs.

Has VJD been considered?

The ICC committee apparently were not too keen on advocating the VJD system as they had found no flaws in the DLS method. However, Jayadevan protested that he was not given a fair hearing.

How South Africa blundered DL method in 2003 World Cup?

The South Africa vs Sri Lanka clash in the 2003 ICC Cricket World Cup was a classic case of misreading the fine print. With rain falling, South Africa assumed they had to reach 229 after the end of 45 overs if the match was called off. Mark Boucher hit a six off Muttiah Muralitharan and blocked the last ball. However, 229 was the par score. South Africa needed to score 230 to win. In the DLS method, when the sheet is handed out, the par score is written. The target is plus 1 the par score. South Africa thought 229 was the target but it was 230. The match ended in a tie and South Africa’s hopes quashed due to a mathematical misjudgment.