Twenty20 cricket April 7, 2016

Why not measure the T20 batting strike rate in 120 balls?

Siddharth Banka
A batsman's destructive power is better highlighted if we take into account the actual length of an innings

Virat Kohli's "120 strike rate" against Australia in a chase of 161 was 192.9. The rest of his team combined had a "120 strike rate" of 138.7. That is, without Kohli India would have ended 22 short © Associated Press

In cricket, numbers matter as much as style, flair and grace. If Sir Don Bradman is the Shakespeare of cricket, then "99.94" is its "to be or not to be". There are many statistics in cricket, some more "significant" than others. Why do we care more about the asking rate at the start of a chase but base our calculations on runs v balls towards the death? The answer perhaps lies in our preference for data that is simple and requires least additional computation to provide a meaningful inference. A good statistical measure in cricket should give the relevant information in an intuitive form to easily assess the state of a game or contribution of an individual.

Batting strike rate - number of runs scored per 100 balls - is probably the most frequently referred to statistic in T20s. Its bowling equivalent is the economy rate, average number of runs conceded per over. How do these two measures measure against each other? Shane Watson, who hung his boots recently as the No. 1 ranked T20I allrounder, has a career bowling economy rate of 7.65. That tells me straight away that in every T20I over, Watson conceded an average of 7.65 runs without having to do any additional mental maths - simple and clear. However, it is harder to extract the intrinsic meaning of his batting strike rate of 145.32.

Batting strike rate is a useful barometer of the destructive power of batsmen in limited-over formats. Chris Gayle's career T20 strike rate of 150.11 clearly shows why is he feared by his opponents more than his opening partner, Johnson Charles, who strikes 119.76 runs per 100 balls, is. However, batting strike rate lacks the inherent meaning that a bowling economy rate carries. This is because batting strike rate is out of sync with rest of cricket. Strik -rate is a decimal measurement but cricket ticks in units of six (balls per over). Calculating a batsman's impact with strike rate in per cent is similar to measuring speed of your car in miles/100 minutes.

Can we do any better? I think we can, especially in T20s, by measuring the strike rate in units of 120, rather than 100 balls. A "120 strike rate" will reveal that Jason Roy's inning of 43 in 16 balls against South Africa in the World T20 was equivalent to scoring 322.5 in an entire T20 inning of 120 balls. Compare the meaning of this stat with Roy's traditional strike rate of 268.7 for that innings. Which number reflects the impact of his innings more easily?

Or think about Virat Kohli's masterful 82 not out off 51 balls against Australia in the same tournament. He clocked a 120 strike rate of 192.9 in a chase of 161. Relate that with the combined 120 strike rate of 138.7 for his team-mates in the same match and immediately you can see that, statistically, India would have fallen short by nearly 22 runs without Kohli.

You may ask, similar to bowlers, why not have an over-based strike rate for batsmen too? However, unlike bowlers, a batsman's unit of performance is not an over. Most consequential batting innings last longer than an over (even in T20s) and, therefore, measuring the rate of scoring runs per over is unintuitive and less meaningful.

In my opinion, 120 strike rate should replace the traditional strike rate in T20s as it resonates much better with the game, feels more intuitive and has extra information built into it.

Siddharth Banka, a clinical geneticist, is a clinical senior lecturer at the Manchester Centre for Genomic Medicine

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