The umpires, who officiated in the 2011 World Cup in the subcontinent, say one way to tighten the system is to use hot-spot cameras to make the system near-perfect.

The International Cricket Council (ICC) maintains that the UDRS has helped to improve the accuracy of the decisions by more than seven percent in the World Cup.

An ICC Elite Panel umpire, not wanting to be named, told IANS that the UDRS has to be foolproof if the players have to accept its decision without any reservations.

"We are still not convinced about the system. It is not a foolproof review system. We feel the introduction of hot-spot cameras would make the system a lot better," said the umpire.

Some teams, including India, have been at the receiving end of the review system, but at the same time, others have benefitted. Much depended on the judicious use of the technology by the teams.

Another umpire agreed with his colleague.
"It is like a lottery. If you are lucky it will go your way, but if you are not lucky then you are done in by the system. It is not possible for the UDRS to take the actual ground factors into consideration and predict if the ball is going on to hit the stumps in case of an lbw," said the umpire, also on condition of anonymity.

Former international umpire K. Hariharan told IANS that in the cases of lbw, like it was clearly revealed when Sachin Tendulkar successfully challenged the umpire Ian Gould's decision during the India-Pakistan semifinal at Mohali Wednesday, the UDRS is not 100 percent accurate.

“The line of the ball till it hits the pad is actual, but from there on its trajectory towards the stumps is all imagination. And whether the ball is going on to hit the stumps depends on lot a of things like hardness of the pitch, air speed and angle at which the ball hits the pad.

"Umpires give lbw decisions imagining that line of the ball and UDRS is also following the trajectory. No doubt the technology is helping to reduce the number of errors, but it should be 100 percent accurate,” Hariharan said.

Sri Lankan umpire Asoka De Silva did not feature in any of the World Cup knockout matches after a string of UDRS reversals of his on-field decisions.

Dhoni has termed UDRS "adulteration of technology with human thinking".
The comment came after England batsman Ian Bell survived an lbw and was declared not out because the distance between the wicket and point of impact was more than 2.5 metres. On-field umpire Billy Bowden stood by his original decision. As per the rule, the on-field umpire had the final word in the case. However, there were a couple instances where the umpires stuck to their decisions even after the UDRS pointed to the distance factor. 

Dhoni’s comments sparked a debate and ICC general manager (Cricket) Dave Richardson, a former South African wicketkeeper, publicly justified the system. The ICC issued fresh guidelines to umpires on the use of the 2.5m rule.

"There are a set of rules along with the Hawk Eye to assist in making the decision when UDRS is implemented. Most of the time, a player is not fully aware of all the rules," Richardson said.

"If Dhoni is made aware of the specifications of these rules, then I am sure that he will accept the decision that was made," he said.

The Board of Control for Cricket in India (BCCI), however, joined issue and stood by the captain.

"BCCI has consistently opposed usage of UDRS. BCCI has not been convinced about the technical adequacy of the system. A presentation made by Hawk Eye to BCCI where Mr. S. Venkataraghavan, former International umpire and Director of Umpires, BCCI, was present, was not convincing and the suppliers of the technology themselves felt 'a leap of faith' was necessary in order to accept the system," board secretary N. Srinivasan said in a strongly worded letter to the ICC.

"The inadequacy of the UDRS has been exposed in this edition of the World Cup. The group stage match between India and England was a case in point which clearly brought out the inadequacy of the system," the letter added.

Even an ardent UDRS supporter, Sri Lanka captain  Kumar Sangakkara, was highly critical of the ICC for altering the 2.5 metre rule in the middle of the World Cup.