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Sunday, April 1

GK: Understanding Ball Tampering (SCIENCE & TECHNOLOGY)


At the heart of the scandal that has already cost one of the world’s all-time greats his captaincy and now threatens to end his career, lies an attempt to illegally change the condition of the cricket ball using a foreign object at Cape Town on Saturday. After cameras picked up Australia’s Cameron Bancroft with a small yellow object in his hand, and rubbing the rough side of the ball as opposed to the shiny side, captain Steven Smith pleaded guilty to ball-tampering.

Why do fielding sides try to keep one side of the ball shiny, the other rough?

In the first 10-15 overs, bowlers generally focus on conventional swing, when the ball moves towards the dull, or non-shiny, side. For inswing, the seam needs to point to leg slip; for outswing, towards first slip. To move the ball in the air, a subtle change of grip is needed. But the seam of the machine-stitched Kookaburra balls, the kind being used in the ongoing South Africa-Australia series, merges with the leather sooner than the hand-stitched Dukes and SGs, both of which have more pronounced seams. This results in the ball going flat, and bowlers find it difficult to move it in the air. That is why bowlers are desperate to extract reverse swing as early as possible. For this, the ball has to be rough on the one side and shiny on the other. Designated ball tenderers in the team ensure this.

What is reverse swing?

It’s the term used for unconventional swingwhen the (old) ball moves in the direction of the shiny side. Due to friction, air passes over the shiny side quicker than it does on the rough side, creating a drag effect that ensures the ball moves in the direction of the shine. This is also dependent on keeping the shiny side heavier, which is done by constantly applying sweat on the shiny side while leaving the rough side completely dry.



Do roughed-up balls automatically start reversing?

No — because if they did, there’d be greats like Wasim Akram and Waqar Younis in every team in every era. To begin with, the ball has to be delivered at over 85 mph (137 kph), so the batsman has no time to adjust to the late movement. To generate that late movement, the action must be slightly whippier or slingier like Waqar Younis’s. Bowling into the wind assists movement towards the shiny side; a ball going downwind encounters no resistance, and its swing is curtailed.

What are the ways to keep one side of the ball shiny and the other side rough?

The only legal way available is to polish the ball using plain saliva or sweat — and ensuring that the other side does not get any moisture at all. Designated ball-shiners are in charge of “making” or “keeping” the ball. The roughness of the other side must be ‘natural’ — the result of wear and tear in the normal course of the game.



What foreign objects have been used to illegally roughen the ball?

Cricketers have used tiny blades hidden in the protective tape worn on fingers, zippers of trousers, bottlecaps, sandpaper, and shoe spikes — or simply rubbed the ball against any rough surface available. Bancroft introduced to cricket yellow tape with great adhesive qualities. Fingernails have been used widely — it is often the team strategy to toss the ball around among four or five fielders before the bowler gets it back, each of whom gets in at least one scratch on the rough side with their fingernails. There are also rogue throws from the boundary, ensuring the ball lands on the pitch square, which is the hardest part of the cricket field. Bowlers also “accidentally” lay their spikes on the ball; two days before the Bancroft incident, Australian quick Pat Cummins’s foot was found to be resting — by “mistake”, he said — for a few extra seconds on the ball.

And are there illegal ways to keep the ball shiny as well?

Players have long used mints that produce a pasty mix with saliva, the thickness of which makes the shiny side of the ball heavier, and assists greater reverse swing. This “slurp-up” tampering technique is believed to have been discovered in England, and was picked up by players the world over. Indian domestic cricketers identified the hard candy Alpenliebe as the ideal sweets to suck on, followed by Poppins. In 2008, the former England opener Marcus Trescothick admitted to having used Murray Mints when he was his team’s ball-shiner during the 2005 Ashes series, when England regained the urn after nearly two decades. Most recently in 2016, South Africa captain
Faf du Plessis was fined for ball tampering after being caught sucking on mints.

Other commonly used illegal ball-shiners include hair gel, sun tan lotion, lip balm, jellybeans or Vaseline. Former South African spinner Pat Symcox allegedly managed to both rough up and shine the ball by sticking it inside his shirt and rubbing it in his armpit.

But how have players been getting away with these acts for so many years?

As with most things, there is a technique to scuffing up the ball, and the really smart cricketers are able to use their fingernails without letting the umpires catch on. The scratches, for example, might leave concentric circles on the rough side, which resemble natural wear and tear. Things used to be somewhat easier before umpires started to insist on holding the ball during drinks breaks, and cameras at the ground became increasingly all-seeing. Another common ploy was to get the most ‘innocent-looking’ player to work on the ball — the jury is out on whether Bancroft fits that description. With ball-tampering of this kind being fairly common, what probably stands out in the Cape Town affair is the brazenness of Australian action — trying to scuff up the ball as nearly 30 cameras zoomed on to every move they made on the field, and the manner in which Bancroft stuck the yellow tape inside his trousers.

The ICC has always been a step behind the practitioners of illegal techniques — which is the reason it has failed to snuff it out for good. The ball-tampering law, Law 41.3.2.1 of the ICC Men’s Test Match Playing Conditions, is rather general, allowing a fielder to “polish the ball on his clothing provided that no artificial substance is used and that such polishing wastes no time”. In the circumstances, it is often broadcasters who end up playing the unofficial police where ball tampering attempts are involved.

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Physics of Swing: The rough side slows down the air due to friction whereas the smoother side allows the air to pass by at a greater speed. According to Bernoulli's principle, greater the air speed, lesser the pressure. So there is a pressure differential that pushes the ball in the direction of the smoother side.

Credit: Indian Express Explained

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