There has been lot of questions about the proposed Duckworth-Lewis method ever since it was introduced back in 1997. The method has modified recently for a better accuracy and it is now known as Duckworth-Lewis-Stern (D/L/S) method.
The D/L/S method is being implemented in the ongoing World CUp and it was implemented in South Africa vs Pakistan match earlier today. Even though Pakistan got all out after the overs are reduced to 47 overs per side. Why did South Africa get extra runs in their target to chase?
Basically D/L/S method considers only two things, the number of overs and the number of wickets left. The method also doesn’t consider a team getting bowled out before the end of innings but it calculates the target when the rain interruption occurs.
Since the rain occured at 40.1 overs with Pakistan still having 5 wickets in hand. The resources to be lost by Pakistan is 3 overs and the compensation runs for those overs will be added based on the percentage calculated.
If the overs are reduced before the first ball is bowled then the game will have no effect of D/L/S method. Since Pakistan will lose 3 overs only after playing 40 overs, they were given 4% increase to the runs they scored at the end of the innings.
4% increase results in 9 runs which took Pakistan score to 231 if the match was originally 47 overs before the game started. D/L method thus neutralises the advantage of chasing team by doing the perfect simulation.
The target will always increase if the overs are reduced while batting first since the team batting first will play thinking they have 50 overs to play.