The
Art And Science Of Ball Tampering
What are the benefits of ball tampering and can it be controlled?
Nowadays,
whenever ball tampering is mentioned, cricket fans immediately relate
it to illegal roughening of the ball’s surface. The recent ball
tampering controversies have just reiterated this ongoing problem
which first surfaced in the early 1990’s. Of course, ball tampering
is not restricted to this roughening activity. In prior years, bowlers
have also been accused of using foreign substances to help shine the
ball and of picking and raising the primary seam. So why do bowlers
tamper with the ball? Does it really help, and if so, in what way?
Are there any scientific facts that support the observations? What
do the current cricket laws state, and are they enforceable? All these
questions are addressed here together with some suggestions on what
changes the cricketing authorities may want to consider.
Law
42 (Fair and unfair play)
Let us start by first examining what the current cricket laws on
ball tampering actually state. Here is the section of law 42.3 that
relates to polishing, cleaning and roughening the cricket ball.
42.3 The match ball - changing its condition
(a) Any fielder may
(i) polish the ball provided that no artificial substance is used
and that such polishing wastes no time.
(ii) remove mud from the ball under the supervision of the umpire.
(iii) dry a wet ball on a towel.
(b) It is unfair for anyone to rub the ball on the ground for any
reason, interfere with any of the seams or the surface of the ball,
use any implement, or take any other action whatsoever which is
likely to alter the condition of the ball, except as permitted in
(a) above.
HISTORY
AND THE ART
It was the summer of 1994, right after the infamous Atherton “dirt
in the pocket” incident, when I was summoned to Lord’s
to meet with the TCCB’s Chief Executive and Chairman of the
Cricket Committee. Obviously, the main topics of discussion were
reverse swing and the role of ball tampering in this relatively
new phenomenon. They first showed me several balls that had been
confiscated after the umpires suspected the fielding side of ball
tampering. From what I observed, the most popular forms of tampering
consisted of gouging the surface using foreign objects such as bottle
tops and opening up the quarter seam using fingernails. I explained
to them why bowlers resorted to such tactics and how that affected
the aerodynamics of the ball, especially with regards to reverse
swing. We also discussed how the cricket laws may be changed so
that ball tampering may be prevented. One of the sensible procedures
introduced right away was to instruct the umpires to inspect the
ball very closely at the end of each over. The actual changes to
the laws did not occur until 2000 when Law 42.3 was introduced.
Although the paltry five run penalty and letting the batsmen choose
the replacement ball intrigued many, including myself, at least
the issue was now formally addressed. However, it must be said that
with the results of the recent hearings at the Oval, I cannot see
any umpire enforcing this law, thus rendering it totally useless.
Ball tampering is not a recent innovation by any means. Ever since
I recall watching cricket, bowlers could be seen cleaning and lifting
the primary seam. A prominent primary seam helps movement off the
ground and it is also critical for conventional and reverse swing.
The practice is now prohibited under Law 42.3, but as some players
argue, if polishing of the ball’s surface to retain the original
shine (smoothness) is allowed then why not allow maintenance of
the seam; they do have a point. It is interesting that even the
legal practice of polishing of the ball has not escaped controversy.
In the 1970’s bowlers were accused of using Brylcreem or Vaseline
to help the polishing process. More recently, we heard about special
mints that supposedly make the saliva a better polishing agent.
While these practices make interesting and controversial story lines,
I am not sure that there is much to it in terms of the science.
Saliva and sweat make perfect lubricants and once the outer lacquer
applied to the ball wears off, constant polishing releases the natural
oils from the leather which help the polishing process. In recent
years, ball tampering invariably refers to the act of deliberately
roughening up a balls’ surface. With all the scrutiny from
cricket officials and television cameras, the original form of blatant
tampering has been all but eradicated. Nowadays, the players resort
to smarter tactics such as making a scratch obtained “naturally”
deeper and wider using a finger nail. This form of tampering is
obviously much harder to identify, even with constant inspection
of the ball. Another tactic is to rub the ball against the boundary
boards or the hard surface beyond the grass as it is picked up after
being hit for four or six. In this case it is not always easy to
prove that the act was committed in a deliberate attempt to roughen
the ball. I am definitely not advocating that players resort to
illegal forms of ball tampering, but can the ball be roughened legally?
NASA scientist Rabindra Mehta examining the seams
on a cricket ball. |
LEGAL
ROUGHENING OF THE BALL
One way is to let the batsman hit the boundary boards regularly,
but I am not sure if the team captain will appreciate that very
much. A more acceptable way for the fast bowlers is to grip the
ball with the seam running across the fingers (similar grip to that
of a spinner) and then bowl with a regular action. In this case
the ball will fly through the air with the seam scrambled (spinning
backwards). If the ball lands on the seam, especially the edge,
the ball will tend to take-off steeply, a lethal delivery that worked
wonders for me on many occasions. Of course, with the seam occupying
a relatively small area of the ball surface, it is more likely that
the ball will land on the leather part thus helping to roughen it
up. The down side to this technique is that there is no control
over which side (the one that is being polished or the one you want
to rough up) hits the ground. A more controlled delivery for roughening
the ball surface is one where the ball is held with the fingers
on the seam and released with a wide arm action such that the ball
spins along the seam with it angled at about 45 degrees to the ground.
The ball is obviously released with the side you are trying to rough
up facing the ground. Yet another option is to put on a spinner
and make him bowl “floaters” with the seam in the horizontal
plane and the rough side facing the ground (see figure 1). So why
go to such great lengths to create a rough surface and is there
any science to support all this?
THE
SCIENCE BEHIND IT ALL
Perhaps the biggest misconception about reverse swing is that it
can only be generated with an old ball, and so to obtain it early
in the innings, one must tamper with the ball. The fact is that
reverse swing can be obtained even with a brand new ball. The slight
problem is that one would have to bowl at around 90mph or higher
in order to get the new ball to reverse swing. Not a problem for
the likes of Shoaib Akhtar and Brett Lee, but what about all the
other mere mortals who cannot achieve those bowling speeds? Well,
that is where the rough surface comes in. As shown in Figure 2,
for reverse swing the ball is released in the same manner as for
conventional swing, but it swings in a direction that is opposed
to that of the seam. The main point to note is that as the surface
roughness on the side facing the batsman is increased, the speed
at which reverse swing is obtained is decreased. Additionally, the
amount of reverse swing obtained at bowling speeds above this critical
value is also increased. Another advantage of creating a rough surface
and maintaining the other side smooth is that contrast swing (The
Wisden Cricketer, Vol. 3, No. 7, pp. 50-53, April 2006) can now
be added to the bowler’s arsenal.
SOLUTIONS?
So can anything be done about the ball tampering problem? Well,
if the cricketing authorities (ICC and MCC) really feel that this
whole tampering issue is totally out of hand, and moreover, they
are really at a loss as to what can be done to control it, I have
a couple of possible solutions. If they feel that reverse and contrast
swing need to be curtailed, then give the fielding side a new ball
after every 10 overs. However, if the consensus is that conventional,
reverse and contrast swing ought to play a bigger role in modern
day cricket, then give them what I call the “Happy Swinger,”
which has one side smooth and the other rough (‘dimpled’
with small holes punched through the leather, as shown in Figure
3) --- a real dream come true for all fast bowlers!
Rabindra Mehta
Sports Aerodynamics Consultant and NASA Scientist based in California.
(rabi44@aol.com)
