The Duckworth-Lewis-Stern, or DLS, method in cricket is a formula devised to arrive at par and revised target scores for a side batting first or chasing, taking into account the resources in hand in the case of rain-affected matches in limited-overs cricket.
In plain English: it’s one of the most mysterious aspects of the game, that even players and umpires themselves struggle to understand at times.
And we’re here to explain how the DLS method in cricket works, and everything you need to know about it.
- 1 History of the DLS method in cricket
- 2 What is the Duckworth-Lewis-Stern method?
- 3 The mathematical formula behind the DLS system
- 4 Previous models prior to the DLS method
- 5 Criticism of the DLS method
History of the DLS method in cricket
Two English statisticians, Frank Duckworth and Tony Lewis, invented this technique. The intention was to give a meaningful, or rather, relevant touch to how the adjusted scores must be calculated if rain or, in some scenarios, bad light cuts down the playing overs and amends the stipulations.
It was introduced in 1997, and the International Cricket Council (ICC) accepted it in 1999. Steve Stern became the custodian of the D/L method, as it was once called, in 2014, adding an S to its title that stands for Stern.
What is the Duckworth-Lewis-Stern method?
This model rightly sets a base for itself with the consideration that the teams have two resources to score runs: the balls available to them and the wickets in hand.
When the rain interrupts the play at any given moment, a team's capacity to add runs to their total solely lies on these two resources, as per the DLS method in cricket.
Let's say rain affects the side batting first. As it will still obviously have a few resources available, the DLS method will take the score of the team a few notches up, depending on the quantity of these resources left at the end of the innings, and a revised total will be set.
In another scenario, if the rain announces its presence in the second inning, the target for the chasing team will be reduced, as in this case, their resources will be depleted. This is why the teams like to chase if there are any chances of rain, so that they are always in sync with the revised target.
These situations, as stated above, will come into effect if rain or bad light shortens the affair, or, in the literal sense, if overs are reduced by the cause of it.
Also, thought is given to the importance of overs. The cricket nerd in you could be shouting “How dare you! Every over is as significant as the other!” But the DLS method in cricket does not agree.
The final overs of an inning are where the batters go after everything. The match situation here generally does not mean much, and scoring runs at a brisk pace is what a batter would intend to do.
Counting this as a factor, the DLS method adjusts the score accordingly and gives it greater weight in a positive connotation for the batting team if they lose out on the slog overs.
To get a better understanding of it, one can elucidate that a team that does not come to bat after the 45th over because of rain has a better chance of finishing with a higher revised total than the team that gets to play the final overs but also bats for only 45 overs.
The mathematical formula behind the DLS system
Naturally, the DLS method in cricket is derived from a mathematical formula. It decides the par score and revised target by calculating the runs scored by both teams, assuming that they have equal resources.
A par score is the one where a team should reach at X wickets down and Y deliveries left at the time of interruption for them to win the match. A revised target is the amended total given to the team after the interference.
Imagine that Team 1 and Team 2 played a rain-affected fixture.
In mathematical expression, the formula is: Team 2's par score = Team 1's score x (Team 2's resources/Team 1's resources).
If the first inning gets completed without a rain interruption, Team 2's DLS par score will be Team 1's final score minus Team 2's resource left.
Despite the formula being known, an individual cannot calculate the par score. Software calculates resources available and resources utilised, and these values are not made public.
If New Zealand's innings concludes on 211 for 5 in 46.1 overs, the 46-over target for India would be 237.— ESPNcricinfo (@ESPNcricinfo) July 9, 2019
If India's innings is reduced to 20 overs, their target would be 148.
Live report: https://t.co/6GSzid5Ewc #INDvNZ | #CWC19 pic.twitter.com/zGuvaWcZPW
Previous models prior to the DLS method
The DLS method in cricket replaced the Average Run Rate and Most Productive Overs methods.
1. Average Run Rate Method
It calculated the revised target for the team batting second. If the overs are reduced, then the chasing side is given the amended target proportional to the average run rate of its opponent.
The formula is: Team 2's revised target = Team 1's average run rate achieved × Overs available to Team 2 + 1.
For example, Team 1 made 300 runs in their 50 overs. This is an average run rate of 6 runs per over. If Team 2's innings are reduced to 30 overs, their new target would be (6 x 30) + 1 =181.
2. Most Productive Overs method
It replaced the ARR method in 1991. If the innings of the chasing team are reduced to X overs, the revised target would be equal to the runs scored by their opponent in their highest-scoring X overs plus 1.
Criticism of the DLS method
The DLS method in cricket is not fool-proof. Though it serves the purpose more correctly than any other model, it has drawbacks of its own.
Firstly, it gives greater weight to wickets than overs. This puts teams better placed to chase, even if they are in pursuit of a huge target, as they can then afford to deliberately slow down their run-scoring.
Another argument that goes against the DLS method is how difficult it is to understand, even for a cricket aficionado.
Recent controversy involving DLS in cricket
The latest Indian Premier League final happened amidst a brouhaha of rain. As the rain poured in the CSK innings after 0.3 overs, the DLS method was used. The over-by-over revised targets for them were:
CSK, the eventual winners, were asked to chase 171 runs in 15 overs. Many fans felt this was unfair, and gave Chennai a heavy advantage.