How the Duckworth-Lewis Method Replaced the Rain Rule: The Full History
Before the Duckworth-Lewis Method (DLS) was adopted in 1997, rain-interrupted ODI matches were resolved by target adjustment rules that produced demonstrably unfair results. The 1992 World Cup semi-final (South Africa needing 22 from 1 ball after a rain break that reduced it from 22 from 13) exposed the absurdity of the previous system. Frank Duckworth and Tony Lewis's mathematical solution replaced it — and the method now carries Stern's name (Duckworth-Lewis-Stern, DLS) after Steven Stern refined it in 2014.
Before DLS, rain interruptions in ODI cricket were handled by several different systems, all of which had significant flaws: (1) Run rate method: the team with the higher run rate at the time of the interruption won; exploited by teams scoring quickly early and protecting wickets, knowing rain might arrive later; (2) Most Productive Overs (MPO): the team chasing was given a target based on the number of overs removed from the first innings, comparing the most productive equivalent overs from the team batting first; this was the system used in the 1992 World Cup that produced the famous South Africa 22-from-1-ball farce.
The 1992 South Africa Controversy
The 1992 World Cup semi-final (Pakistan vs England was the other semi-final; this was South Africa vs England at the SCG): England batted first and scored 252/6 from 45 overs; rain reduced South Africa's target to 22 from 1 ball under the MPO (Most Productive Overs) system. The MPO adjustment removed the most productive over of England's innings (which contained boundaries) and adjusted the target accordingly — the calculation produced a target of 22 from 1 ball, which was physically impossible. South Africa needed 22 from 13 balls before the rain interruption; after the interruption (which removed 12 balls), their target was adjusted to 22 from 1 ball. The result: South Africa effectively eliminated from the World Cup by a rain calculation. This event triggered the ICC's search for a better method.
How DLS Works
DLS in practice: the DLS table assigns a 'resource percentage' to every combination of wickets remaining and overs remaining. When rain interrupts play, the percentage of resource removed is calculated, and the target is adjusted by that percentage. Example: Team A scores 250 in 50 overs (full resource). Rain removes 10 overs from Team B's innings before they bat (so Team B will face 40 overs). The DLS table shows: 10 wickets + 40 overs = approximately 89.8% resource. The DLS par target for Team B is approximately 250 x 0.898 = 224.5, rounded to 225. If the rain removal happens mid-innings (Team B is already batting), both remaining overs and remaining wickets are factored in. If Team B has lost 4 wickets and has 25 overs remaining when rain arrives and removes 10 more overs, the resource calculation uses 6 wickets + 15 overs remaining from the table.
DLS Criticisms
DLS has been criticized in several specific scenarios: (1) It undervalues wickets in T20 cricket — the DLS resource tables were calibrated using ODI scoring patterns, where wickets are more valuable; in T20 cricket, teams often have scoring resources in the lower order that DLS underestimates; (2) It can produce targets that disadvantage teams that correctly play the conditions — a team that conserves wickets deliberately (planning for a death-over acceleration) is 'penalised' by DLS if rain arrives before the acceleration phase, because their current run rate is low and DLS adjusts based on current run rate + resource proportion; (3) Large interventions (reducing to fewer than 20 overs) can produce wildly different targets that seem intuitively disconnected from the match situation. Despite these criticisms, DLS has been universally adopted as the fairest available method for rain-interrupted matches.
Frequently asked questions
What is the Duckworth-Lewis method in cricket?
The Duckworth-Lewis-Stern (DLS) method is the mathematical system used to set revised targets in rain-interrupted limited-overs cricket matches. Developed by statisticians Frank Duckworth and Tony Lewis in the mid-1990s (updated by Steven Stern in 2014, hence 'Stern'), it calculates the proportion of 'scoring resource' (a combination of overs remaining and wickets remaining) that a rain interruption has removed, then adjusts the target by that proportion. DLS replaced the earlier 'Most Productive Overs' system, which produced famously unfair results including the South Africa 22-from-1-ball situation in the 1992 World Cup semi-final. DLS has been in official ICC use since 1997.
What happened in the 1992 World Cup South Africa vs England semi-final?
The 1992 Cricket World Cup semi-final between South Africa and England at the SCG in Sydney produced one of cricket's most famous rain controversies. England batted first and scored 252/6 in 45 overs (the match was already reduced from 50). South Africa was chasing 253 and needed 22 runs from 13 balls when rain stopped play. Under the 'Most Productive Overs' (MPO) rain rule in use at the time, 12 balls were removed from South Africa's innings. The MPO system removed the most productive over from England's total and recalculated the target — the result was that South Africa's target was revised to 22 from 1 ball. Physically impossible to achieve, South Africa were effectively eliminated. The farce directly led to the development of the Duckworth-Lewis Method, adopted in 1997.
What is par score in cricket?
Par score in DLS-affected cricket matches is the target score that Team B must reach at any point in their innings to be winning the match if it were to be abandoned. The DLS system calculates a 'par score' for every stage of the innings (after each ball) based on the resource remaining. If rain arrives at any point and the match is abandoned (cannot be completed), the team whose score is above the DLS par score is declared the winner. For example, if Team A scored 250 and Team B needs 200 from 40 overs (DLS revised target), but at over 20 (half the innings), Team B is on 110 with 6 wickets down, the par score at that moment might be 100 — Team B is above par and would win if the match were abandoned.