Cricket’s Jerks, Angles and Extensions or Not Throwing a Tantrum

(This post is one of a series which began here, yesterday.  Readers my wish to start there )

Last Thursday it was Info Day at Eastern Institute of Technology, Hawkes Bay, NZ.    So, the Squire, shunning conventional means of travel, and saving the CO2s, waited ‘til Friday morning before joining Third Man in the Type III to travel back in time to the EIT Info Day.

A little secret here: the co-ordinates were already set in the ‘My Favourite Places’ section of the Squire’s terrestrial navigation device that Her Grace gave Him for Christmas. 

Not EIT exactly, but Te Mata, and the other Buck House, Coleraine, pictured above,  across the road from the winery, designed by the Wellington architect Ian Athfield,  who incidentally also designed a modest C20th ‘extension’ to the East Wing of the Great House for the Squire.

Stretching his legs after the short but naturally debilitating passage and savouring a well aged bottle of Coleraine, the Squire, in improving humour, awaited the arrival of his very good friend the biomechanic, Professor Bob Marshall.

“A little light background reading, Third Man, please …”

The 1947 code (4th Edition, 1970): Law 26b states thata ball shall be deemed to have been thrown if, in the opinion of either umpire, the process of straightening the bowling arm, whether it be partial or complete, takes place during that part of the delivery swing which directly precedes the ball leading the hand. This definition shall not debar a bowler from the use of the wrist in the delivery swing.”

This set elbow extension as an anatomical constraint and ‘just prior to release’ as a impractically vague temporal constraint. 

So a new code Law 24.3 in 2000 sought to clarify thisA ball is fairly delivered in respect of the arm if, once the bowler’s arm has reached the level of the shoulder in the delivery swing, the elbow joint is not straightened partially or completely from that point until the ball has left the hand. This definition shall not debar a bowler from flexing or rotating the wrist in the delivery swing.

By 2000, biomechanics had already revealed that, under the constraint that any straightening of the arm prior to release was evidence of throwing, almost no bowlers operating in the first class game could meet the restriction.

The ICC therefore chose to specify a range of elbow extension tolerance levels that it considered acceptable, but which were dependent on ball release speed.  Fast bowlers would be allowed 10° elbow extension, medium pace bowlers 7.5°, and spin bowlers only 5°.  Poor umpires !

In 2004 Rene Ferdinands and Uwe Kersting published Elbow Angle Extension and implications for the legality of the bowling action in Cricket.

For their research sixty-nine bowlers were selected and grouped into fast, med-fast, medium, slow, and finger-spin categories. 40% of these were first class or test cricketers.  8 bowlers in their sample were observed as possibly having a “throwing-type” or “jerky” action.  

Ferdinands and Kersting quickly confirmed that the elbow angle extension operations of none of their 69 could meet the provisions of the 2000 code.  Further, although 100% of the medium bowlers met the ICC’s constraints, only 86.7% of the fast, 87.5% of the fast/medium, 35.7% of the slow and 60% of the spin bowlers satisfied the 10, 7 and 5% limits respectively.

At this point the ICC could have required bowlers such as these to alter their actions to meet the prescribed constraints or they could have eased the maximum angles to ‘legalise’ a greater proportion.  They chose the later. 

Nor did they appear to consider that they might not be basing their decisions on a ‘reliable’ sample.   Of the 69, 28 had come through the trial by batsman to become first class or Test bowlers, a process that selects not for legitimacy of action but for effectiveness.

Increased elbow extension benefits quick bowlers for speed, but also facilitates humerus internal rotation which, for spinners, improves rotation speeds and wrist flexibility.  The former considerably aids turn, drift and dip.  The latter increases the potential to bowl deliveries such as the doosra.

The authorities chose to set the limit at 1) a one-angle-fits-all i.e. regardless of bowling style, thus, avoiding issues of interpretation as to style of bowling, 2) at a extent of angle that would allow accurate observation – floppy long sleeved shirts and all, and 3) at an angle, incidentally, that identified as legal all but one of the 8  ‘throwers’ in the sample.  This was 15 degrees.

Professional bowlers are capable of modifying their actions to gain the maximum permitted advantage.  Like speeding drivers they will see a ‘limit’ as a target if it increases their performance. Without an ‘on field’ or ‘non-lab conditions’ means of measurement bowlers will naturally risk grabbing a few extra degrees.

Also they are capable of reducing the elbow angle extensions if they should need to.  Almost all of those who have been sited and worked on their action have had their ‘new’ actions cleared; evidence that those who earn a significant income from bowling can alter their elbow angle extension.

The authorities ignored the opportunity to demand improved actions.  For instance they could have set the elbow angle extension limit at 10%.  This would have required 13.3% of the fast bowlers, 12.5% of the fast/medium and 40% of the spinners in the sample to modify their actions.

Interestingly and significantly in the ‘throwing’ group of 8 only one extra bowler would have been ‘excluded’ by a reduction from 15% to 10%.  Clearly for this group it is not elbow angle extension that causes the cricketing purist to wince and cry ‘jerk’.

Does this mean, as they and their supporters will claim, that many of those whose actions look really bad are in fact bowling fairly?

“Well,” said the Squire, “that is why we are here in Hawkes Bay, waiting for my old cuz Bob.  He’ll be along soon, but until then there’s another bottle of Buck’s best to enjoy.”



Filed under Light roller

6 responses to “Cricket’s Jerks, Angles and Extensions or Not Throwing a Tantrum

  1. growltiger

    It is clearly not so much the angle as the finer elements of the physics of chucking that offend us purists. There is an immense difference between someone Graeme Swann (or Lock at the end of his career) bowling with a classical sweep of the arm, and a bowler like Ajmal, who is characterised by the pause and jerk method. I have very little doubt that the balls of “deceptive length” (batsman expects it to be short, and gets yorked playing across the line) are pretty much what the youthful Tony Lock delivered to Doug Insole. But I would be very surprised if it takes Ajmal more than 15 degrees of flexion to achieve it, which means that complying with the existing flexion limit is a necessary (but not sufficient) condition for fair bowling.

    It is no doubt interesting that bowlers whom everyone accepts as paragons also flex, but this fact should alone have suggested to the legislators (and the biomechanists) that flexion was not the whole story. Instead of legitimating seven out of the eight obvious chuckers, they ought to have analysed more deeply what made the eight chuckers intuitively different from all of the legitimate bowlers.

    For instance, what matters, for the Ajmal type of length-deception, is the amount of javelin-like acceleration of the hand as it goes through. What should be measured is how much that actual acceleration exceeds what the same bowler would achieve if his arm were actually straight, and were rotating about the shoulder at the same speed as the upper arm actually rotated in the offending delivery. The angle of flexion does not figure in this calculation, incidentally (although it might be inferred from the answer).

    Note, by the way, there is no objection to any of the many varieties of slower ball that quick bowlers use to bamboozle twenty-twenty batsmen. They almost all rely on doing things that reduce the amount of energy imparted to the ball at release, but without changing the normality (or purity) of the action.

  2. Dear GT,
    Thank you for positing this full comment. Shortly TM will post the next piece in this series which does actually start with Lock. By the post after that one we should be onto the ‘factor’ that you identify.
    Hope you continue to comment as the series progresses.
    What is proving diffcult to communicate is the way that the sample that the ICC has relied on as ‘normal’ includes players who probably developed increased angles of extension and other techniques in order to get any turn at all on the average first class wicket … to concluded that whatever system is used must be designed to allow most of these to qualify as legitimate is the fundamental error, and the step on the slippery slope. Slope? See next post.

  3. Pingback: Throwing in Cricket – UnLocking the Evidence | Down At Third Man

  4. diogenes

    on an earlier post, I brought up the case of Loader who was never, I believe, called for throwing but who was widely believed on the county circuit to throw 2 deliveries – his bouncer and his slower ball – a variety of off-break, I seem to recall reading passim. I imagine his slower ball might well have fallen into growltiger’s “pause and jerk” method but I cannot find any footage of his action.

  5. growltiger

    I only saw Loader bowl once, and wasn’t old enough to understand the finer points. Moreover, he was wearing at least three sweaters, which probably masked quite a lot of subtle biomechanical deviation. However, my memory is that his action was pretty smooth, suggesting that he didn’t try either of his special deliveries that day.

  6. Pingback: The Curious Incident of the Angle that Did Not Exceed 15 Degrees | Down At Third Man

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