Instruments quantitatius

The following section discusses a finger spin delivery scenario, illustrating a bowling delivery with inputs extrapolated from the quadratic regression analysis (Table 7.2). A bowling line of 0.1068 m, length of 4.4 m and release speed of 57.4 mph are used, with a deviation angle of 2.2°, deviating away from the opposing batter (Figure 7.9).

Suppose an SLA bowler delivers a ball to an RHB (Figure 7.7c) at a release speed of 57.4 mph. This delivery will slow down during flight (due to drag) and at contact with the pitch (due to friction). The delivery however can still be expected to retain 90.2 to 87.1%

of its initial release speed (James et al., 2005; Figure 7.8).

Figure 7.8 - An illustration of the ball impact and rebound velocity (mph)

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If an opposing batsman of average height were to adopt a stride length of 0.5 m from the batting crease (see Stuelcken et al., 2005; Stretch et al., 1998), whilst playing a defensive shot with the bat a short distance in front of the pad (to minimise the ball striking the pad), we can assume an intercept location of 2.5 m from a delivery pitching at a length of 4.4m, over a duration of 104 – 107 ms (Figure 7.9a).

As the batsman’s aim is to meet the bat to the ball in its longitudinal axis or ‘sweet spot’

at bounce (Figure 7.9b) i.e. 54 mm from the bats edge (Peploe et al., 2018); and if the batsman plays down the line of its original trajectory, the ball will only need to deviate by 2.2° in order to miss or take the edge of the opposing batsman’s bat. This equates a transverse distance of 0.092 m over a distance of 2.5 m (Figure 7.9a). Furthermore, if the ball is delivered on a leg stump line (e.g. + 0.1068 m from the centre line of middle stump), the predicted ball path would strike the stumps having deviated a transverse distance of 0.17 m. This may bring multiple forms of wicket taking opportunities into play, namely leg before wicket (LBW).

Figure 7.9 - (a) a schematic diagram of ball trajectory for a delivery deviating 2.2°, showcasing the effectiveness of deliveries deviating away from the opposing batsman and the time constraints if released at 57.4 mph; (b) an illustration representing the dimension of a cricket bat and the distance between the its centre and the bats edge.

(a) (b)

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The batsman’s ability to intercept a deviating delivery such as this is extremely problematic as the magnitude of deviation and ball release speed may significantly affect the time taken for the motor system to respond to the new visual stimulus; defined as the

‘visual-motor delay’ (McLeod, 1987). In this scenario, the successful interception of the ball therefore depends more so on the accuracy of batman’s adaptations to the deviating ball, than on anticipated knowledge of its impact location. Whilst visual-motor delays have reported to be as low as 55 – 130 ms (see Lee et al., 1983; Bootsma & van Wieringen, 1990), batsman have been reported to be unable to alter their shot within 200 ms of ball arrival (McLeod, 1987), as the inertia of the cricket bat precludes a faster response (Land & McLeod, 2000).

As this delivery scenario illustrated in Figure 7.9a falls within the reported 200 ms threshold, this suggests that a batsman may be unable to adjust successfully and intercept the deviating delivery, both constraining bat-ball execution, reducing run scoring opportunity and significantly increasing the wicket taking opportunity of the bowler.

Whilst deliveries with greater angles of deviation may have a heightened probability of missing the opposing stumps, the distance the end effector is required to adjust, within this finite window, may be sufficiently greater.

Notably, no parameters were entered into the quadratic regression equation for bowling average, indicating that the variance in an elite finger spin bowling average within test cricket is unable to be explained using the parameters investigated within this study. This signifies that bowling average may be an unstable performance metric in which to predict finger spin bowling performance in international test cricket, due to the unpredictable response of an batsman to an oncoming delivery (as highlighted by the low bowling average observed for deliveries pitched <1m in length (Figure 7.4a)). It is plausible other factors may be associated with a bowler’s ability to form a low bowling average which may account for the unexplained variation within the data. These may include: the context of the game, the ability or pressure applied on the opposing batsman, playing conditions and field placings; all of which were outside the scope of this study and warrant further investigation in future studies.

One of the limitations of using Hawkeye ball trajectory data to investigate the effects of bowling parameters on performance is ball spin rates were unobtainable and therefore

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outside of the jurisdiction of investigation in this study. As described, the trajectory of ball flight is highly dependent on the ball’s direction and magnitude of the ball’s rotation.

In addition, the current study neglected to investigate the effects of bowling parameters in differing playing conditions. Differences in pitch conditions are frequent within professional cricket and linked to the organic composition of the soil and preparation of the surface (see James et al., 2005). As such, previous work has shown that spin bowlers may alter their release characteristics e.g. deliver speed, in differing conditions and thus may impact upon bowling tactics (Crowther et al., 2018). Finally, three of the finger spin bowlers within the sample have been known to utilise the carrom-ball bowling variation.

Here the ball deviates away from the batters of the same hand dominance. It was outside the scope of this study to determine these deliveries within the data and were therefore categorised as finger spin deliveries which deviated away as opposed to specific bowling variations.

7.7 Conclusions

The results of this study suggest that the elite finger spin bowlers conceding the least runs released the ball at higher ball release speeds, bowled straight bowling lines and pitched the ball 4 – 5 m in length. Furthermore, deliveries deviating away from the opposing batsman conceded less runs and took more wickets when compared to deliveries deviating toward. The study findings highlight the nature of the contribution of performance analysis in competitive performance contexts and are likely to provide a framework for coaching, player selection and technical pathway development for finger spin bowlers to impact within test match cricket. These findings can support bowler preparation for competition, by enabling practitioners to design more innovative training tasks attuned to test match specific competition demands. As test match spin bowlers develop skill playing professional domestic cricket, future studies should explore whether there is an alignment between factors effecting performance in domestic spin bowling and those effects presented in this study.

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