Cricket, like any other outdoor sport, is hugely dependent on the weather. Rain can often play spoilsport, interrupting matches and affecting targets set by teams. This is where mathematical calculations like the Duckworth-Lewis-Stern (DLS) method and the VJD method come into the picture. They help determine revised targets in rain-affected limited overs matches.
What is the VJD Method?
The VJD method, short for V. Jayadevan method, was proposed by V. Jayadevan, a civil engineer from Kerala, India. It was introduced in the late 2000s as an alternative to the widely used DLS method for recalculating targets in interrupted matches.
The VJD method gained prominence when it was adopted by the Board of Control for Cricket in India (BCCI) for all its domestic limited overs tournaments in 2007. This included high-profile events like the Ranji Trophy and the Vijay Hazare Trophy. The move was seen as a challenge to the ICC-backed DLS method.
How Does the VJD Method Work?
The VJD method relies on two key mathematical curves – the normal score curve and the target score curve.
The normal score curve depicts the expected scoring pattern of a team across the full quota of overs. It takes into account the percentage of runs expected to be scored in various phases of the innings. For example, higher strike rates are expected during the powerplay overs and death overs compared to the middle overs.
The target score curve shows the revised scoring pattern required after a rain interruption resulting in loss of overs. The curve is modelled using historical data and an understanding of how teams modify their approach in such scenarios.
The VJD method thus calculates two parallel curves. The Runs % values from the normal curve are used till the rain interruption. Thereafter, the Runs % values from the steeper target curve are used to determine the par score. The curves account for the changing dynamics of the game.
VJD Method vs DLS Method
The fundamental difference between VJD and DLS lies in how the scoring pattern is modelled.
The DLS method uses a single curve that assumes scoring rates increase linearly as overs progress. VJD’s use of normal and target curves is viewed as more realistic as teams strategise differently and don’t always up the scoring rate in later overs.
Another key difference is DLS factors in wickets lost but VJD does not. The DLS par score changes significantly if more wickets are lost before an interruption. However, VJD maintains the target is only a factor of overs remaining and balls faced.
In practice, both methods yield similar par scores in most scenarios. But VJD is sometimes perceived to be more favorable to the chasing team.
Debate Around Adopting VJD
When the BCCI first adopted VJD, it was expected to be analyzed by the ICC and considered as an alternative to DLS for international cricket.
However, the ICC cricket committee led by Clive Lloyd rejected VJD in 2012. It concluded there was “no evidence of any significant flaws in the DLS method nor did the committee believe that any improvements could be offered by the VJD method”.
Despite this, BCCI has continued using VJD for its domestic tournaments as it is perceived to be more suited to Indian conditions. The IPL initially used DLS but adopted VJD in 2013, only to revert to DLS in 2014.
Over the years, there has been much debate around whether VJD should replace DLS internationally. But recent upgrades to DLS have made it as flexible and dynamic as VJD.
Future of Target Revision Methods
As cricket continues to evolve with new formats and greater use of data analytics, we may see more advanced and accurate rain rule systems emerge. However, any new method will need to win trust before dislodging the established DLS method.
The core challenge is modelling the complex dynamics of a cricket innings. VJD presented an alternative approach with its use of dual curves and phase-wise run scoring percentages. Moving forward, techniques like machine learning may be applied to make projections more context-aware and accurate.
However, the underlying framework of mathematical modelling to maintain fairness and integrity in interrupted games is likely to remain relevant. And the VJD method will be remembered as an innovative idea that challenged the status quo.