How a second look helps!

With the Decision Review System (DRS) in the news for the wrong reasons after the Steve Smith episode in the Bengaluru Test, here is a look at how the technology works.

The Decision Review System has made good progress in the last nine years, after it was first unveiled.   -  GETTY IMAGES

Had a delegation led by ICC General Manager Geoff Allardice — after a research report released by the prestigious Massachusetts Institute of Technology in the United States — along with representatives of Hawk-Eye, the firm that has been evolving one of the key elements of the Decision Review System (DRS), not managed to convince India’s head coach Anil Kumble and others about the credibility of the DRS, the Steve Smith episode or Cheat-gate would not have occurred. After all, until two months ago — after the bitter experience of the Indian team’s DRS debut series in Sri Lanka in 2008 — the BCCI had kept the System at bay. However, midway through the long home season of Test cricket, India embraced the DRS.

Had the ongoing Border-Gavaskar Trophy been played with similar playing conditions as the previous editions of the series, the DRS would have only been discussed if an umpire had given a horrendous decision. Instead, the DRS has found itself in the headlines, thanks to the Cheat-gate where Australia captain Steve Smith dared to consult the dressing room about reviewing a decision during the second Test in Bengaluru. This piece is not about the Cheat-gate, though. Since the use of the DRS itself is in its nascent stage when it comes to India’s cricketers, let’s try and understand how it works:

The evolution of DRS

Ever since the review system, then referred to as the Umpire Decision Review System, was introduced during India’s three-Test series in Sri Lanka nine years ago, it has evolved quite a lot. Back then, most of the technological aids, like the snicko and the ball-tracker, were manually handled. However, thanks to the use of most advanced cameras, the system that is used now has virtually no manual intervention.

When is DRS used?

The primary objective of the DRS was to eliminate howlers in decision-making. However, it has now emerged as a potent weapon, which can not only rectify an umpiring mistake, but at times, also help a doubtful chance to be converted into a dismissal, should the fielding side use it cleverly. The most interesting aspect of the DRS is obviously the leg-before-wicket (lbw) decision, where the system not only zeroes in on the line of the ball, but also the point of impact of the ball on the pad, and more importantly, the predictive path to ascertain whether the ball would have hit the stumps or not.

What are the key elements of DRS?

First and foremost, the third umpire — based on the TV footage provided by the host broadcaster — ascertains the legality of the ball, i.e. confirms that the bowler has not bowled a no-ball. Then, the broadcaster — aided by experts from HawkEye, the firm that has developed Ultra Edge and Ball-Tracker, the two most vital ingredients of the DRS — first shows the Ultra Edge. The umpire can see a split screen view of the front-on and side-on view of the point at which the ball crosses the bat. Additionally, the umpire can also listen to the sound of the ball through stump microphones, which helps him confirm whether the batsman had edged the ball before it thudded into the pad.

How is the predictive path ascertained?

Even before he factors in the ball tracker, the umpire first has to be sure about where the ball has pitched and whether the point of impact is in line with the stumps — unless of course the batsman has not offered a stroke. The last aspect is to check whether the ball would go on to hit the stumps. It is determined based on software calculations that largely rely on various frames of every ball that is bowled during a match. The more the number of split frames available to the technicians and the software the better is the accuracy of the predictive path. So advanced has this technology become that from 50 frames per second during the 2011 World Cup, the Ball Tracker cameras — eight high definition cameras used during every match — can split a second into 340 frames.

If all three of the parameters conclusively show that the ball would hit the stumps, the third umpire has to rule a batsman out, irrespective of the decision made on the field. However, if less than half the ball has either pitched in line of the stumps or hit the batsman’s pads or is only clipping the stumps or bails, then the third umpire sticks to the decision made by the on-field umpire to ensure the human element of adjudication is kept intact.

How is less than 50 per cent of the ball decided?

Till last year, while calculating the predictive path, the width of the stumps used to be calculated from the centre of the off-stump to the centre of the leg-stump. However, since last September, the rules have been amended and the width of the stumps is calculated from the edge of the off-stump to the edge of the leg-stump. The additional distance of 1.9cm on either side has resulted in more number of lbw calls going in bowlers’ favour.