Rain ruined South Africa's dream
The rain rule was used in South Africa's final Group B match against Sri Lanka and sparked criticism after the hosts were eliminated from the tournament.
But Frank Duckworth, who devised the system along with fellow-mathematician Tony Lewis, believes Shaun Pollock's men only have themselves to blame.
"People are always going to be unhappy if they lose," Duckworth said in The Indian Express on Thursday. "South Africa lost because of their own mistakes."
"Both Shaun Pollock and Sanath Jayasuriya (Sri Lankan captain) had the same papers (with the run-rates). Sanath read it right and Shaun didn't," he said.
"As far as we are concerned, the rules were agreed upon by all countries before the Cup and no-one has complained yet."
Bizarre situations can still happen - they could happen under
South Africa's World Cup dream ended in tatters when their match against Sri Lanka resulted in a tie after rain stopped play with five overs remaining at Kingsmead on Monday.
The hosts, needing a win to reach the Super Six stage, were 229 for six after 45 overs in reply to Sri Lanka's 268 for nine when a downpour drove the players off the field.
According to the Duckworth-Lewis method, the "par" score was 229, which meant the honours and the points were shared.
The result meant South Africa missed out on qualification by just one run as they ended up finishing fourth in the group with 14 points.
Batsman Mark Boucher was apparently under the impression the target was 229, not 230, and blocked what turned out to be the last ball of the rain-hit match.
However, it is not the first time South Africa has paid the price for bad weather.
In 1992, they were asked to score an impossible 22 to win off one ball in the rain-affected World Cup semi-final against England in Australia.
"What the 1992 semi-final did was highlight the fact that a logical and mathematical approach was needed to solve the problem," said Duckworth, currently with the Royal Society of Statisticians.
"The prevalent Australian rule was not thought through as much as it should have been."
He also said he was now working on a new system along with Lewis to "avoid a ludicrous and unfair situation".
"Bizarre situations can still happen. They could happen under any rule," he said.
"That's why we are working at an alternative method. Not necessarily a better method, but an alternative method that will focus on probability of victory rather than the margin of victory based on resources in hand.
"We are trying to reach a situation where we can ascertain the probability of victory of both the teams, and set a revised target accordingly."