# Assessment and Measurement of the Side-Effects of an Evidence-Based Intervention with an Advanced Smart Cricket Ball Exemplified by a Case Report on Correcting Illegal Bowling Action

## TL;DR

This study shows how a smart cricket ball can help correct illegal bowling actions and also detect unintended changes in other aspects of a bowler's performance.

## Contribution

The use of a smart cricket ball with gyroscopes to measure side-effects of technical interventions in bowling actions is novel.

## Key findings

- The intervention reduced illegal bowling actions by 15–27% as measured by the precession signal.
- Skill performance parameters improved by 7–53%, while physical parameters like spin rate decreased by ≈10%.
- The center of pressure shifted closer to the palm, and the yaw angle of the angular velocity vector changed significantly.

## Abstract

Correcting an illegal bowling action in cricket through technical intervention involves modifying a movement pattern. This study evaluated the success of an intervention aimed at correcting the suspect actions of two off-spin bowlers and assessed whether it influenced other movement patterns and performance parameters that were not directly targeted by the intervention (the “side-effects” of the intervention). For this purpose, a smart cricket ball equipped with three high-speed gyroscopes was used. This technology not only detects illegal bowling actions but also measures five physical and five skill performance parameters, along with ratios within and across these two parameter groups. Additionally, it tracks the position of the centre of pressure, where torque is applied to the ball, and identifies the type of delivery based on the direction of the angular velocity vector in the global coordinate system. The significant reduction of 15–27% in the integral of the precession signal before the torque spike provided the required evidence for the success of the intervention. Among the performance parameters not targeted by the intervention, skill parameters improved by 7–53% after the intervention relative to before the intervention, while physical performance parameters (spin rate, torque, angular acceleration) decreased (≈10%) significantly after the intervention. The position and vector of the centre of pressure shifted significantly distally and closer to the palm in both bowlers (33.3° and 47.5° in participants A and B, respectively) after the intervention. Although the basic average type of delivery (sidespin plus half swerve, and top-spin plus half swerve) did not change, the yaw angle of the angular velocity vector in the global coordinate system moved significantly counterclockwise by 18–20°. This study demonstrated that while the intervention successfully corrected illegal bowling actions, the smart cricket ball also revealed changes in other performance measures, which aligns with the understanding that the bowling action operates as an integrated, dynamic system.