The History of DLS Method

The DLS method is a mathematical formula designed to calculate the target score for the batting team in a cricket match with limited overs, in case of interruption caused by rain or other such weather conditions, for instance snow, thunderstorm etc. This method was invented by two English statisticians named Mr Frank Duckworth and Mr Tony Lewis. Formerly known as the Duckworth-Lewis Method (DL), it was introduced in 1997, and later became adopted officially by the International Cricket Council in 1999. Later, Professor Steven Stern became the guardian of the method and it was therefore renamed to Duckworth-Lewis-Stern method in November 2014.

Moreover, the DLS method works towards attempting to set a fair target for the team that is chasing in a match affected by bad weather. The vital principle is that each team in a match (limited overs) has two available resources in regards to scoring runs, which are; overs and wickets remaining. The target for the chasing team is adjusted in proportion to the change in the combination of the two resources.

Previously, various different methods were used to accommodate rain-affected matches; the most commonly used were the ‘Average Run Rate Method’ and the ‘Most Productive Overs Method’. These methods were not complex, but had many flaws and were easy to exploit. The former took no notice of the loss of wickets of the team batting second, however it took into account scoring rate upon match interruption. That being said, if the team batting second felt that a rain interruption could be around the corner, they would simply up their scoring rate without giving any heed to the wickets being lost in the process; thus making any comparison between the two teams unjust. Similarly, the latter ignored loss of wickets of the team batting second and took into account the most productive overs which resultantly affected the balance of the match. Hence, both these methods were flawed and disturbed the balance of the match as it paid no attention to the match situation at the time of the interruption.

The ‘Most Productive Overs Method’ was used in the semi-final match in 1992, between South Africa and England. In this match, when the play was stopped for twelve minutes by rain, South Africa required 22 to win from 13 balls (an achievable target). When the play was then resumed, the revised target required South Africa to chase 21 runs with only 1 ball remaining, which was practically impossible, as the maximum a batter can score on 1 ball is 6 runs. The outcome of this match was unfair. Had the D/L method been devised back then, South Africa would have required 5 runs to win and 4 runs to tie from the final ball. This would have certainly resulted in a different and better outcome. It is therefore that the two British statisticians (Frank Duckworth and Tony Lewis) devised this method, which avoids all the flaws that occurred when using the previous two methods.

The D/L method was first used in the second ODI, played between Zimbabwe and England on 1st January, 1997. Zimbabwe emerged victorious in the match by seven runs, but it was not until 1999 that the ICC formally adopted the D/L method as the sole system of calculating target in rain-effected matches. The DLS method certainly brought balance to the matches affected by rain and also ensured fair outcomes.