Cricket is a game rich of stats and numbers. Usually, it needs a lot of it to extract the value of any performance in Cricket and there are reasons for it. (See Cricket - a game of unusually high amount of stats and numbers. Why?)
For decades, there has been a traditional method of recording performance stats to highlight the value of any performance in Cricket and it has served the purpose, somewhat, for Traditional Cricket - Tests and ODIs. That method aims at highlighting certain aspects depending on the nature of Cricket - for example, batting average and bowling strike rates for Tests and combination of batting runs and batting strike rate and combination of wickets and bowling economy for ODIs.
T20 is a bit different in that sense. Unlike other formats of Cricket - Tests and ODIs - players get much shorter time to express their skills and it does not need a player to perform for a relatively longer period to make an impact on the game. The game changes in even just a couple of deliveries. A couple of wickets in quick succession, a maiden over, couple of under-4-runs overs, 3 successive boundaries, a quick fire 25 or 30 runs on 10 balls or even 10 in 3 balls - all of such events, most of the times, result in irreversible impact on the game.
For example, in Tests, a batsman is supposed to either score runs at all costs or don't get out, therefore, the idea of excluding the 'Not Outs' from the calculation of Batting Average looks appropriate. Similarly, the primary objective of bowling in Test Cricket is to take 20 wickets even if it comes at higher economy, so Strike Rate carries higher significance in judging the bowler than economy of his bowling.
In ODIs, a batsman's value is judged mostly by the amount of runs, 100s and 50s scored. Averages or Strike Rates don't catch the eye unless they are either too high or too low but they alone are not used to judge a batsman. In bowling, its the economy and number of wickets that takes the precedence while average and strike rates gets the same consideration as batting average and strike rate.
It all changes in T20. T20 is impact Cricket where a player has to make an impact in a shorter span and has to keep making it in successive spans to avoid getting the initial impact stand neutralized or ineffective. The batting average usually does not carry that much weightage as in Tests or ODIs as it runs scored does not consider to be having an impact unless it is with certain strike rate. In fact, scoring more runs with lower strike rate is what, at times, make it look even worse than not scoring them at all.
Then, the bowling in T20 is seen somewhere in the middle of Tests and ODIs. Like ODIs, the objective is still to restrict the opponents from scoring runs but there is no better and more efficient way of doing it than taking wickets at regular intervals like in Test Cricket. That's what gives the Economy and Bowling Strike Rate more significance while evaluating value of a performance or a player.
T20 Cricket is still evolving but it has already been played enough for some generic performance benchmarks to be set that can be applied to calculate the impact of a performance.
Batting Strike Rate of 130 and an average of 30 is what is generally considered as a benchmark for a good T20 innnings. 50s and 100s still carry its significance as scoring a 50 or a 100 in such a short span has to be considered an achievement in itself as well.
For Bowling, its the Economy of less than 8 runs per over and strike rate of 12 (2 wickets in 4 overs bowled) that can be considered as a benchmark for a good performance.
That's what gave birth to the idea to have a different kind of stats method for T20s that can take meaning of numbers closer to how a performance is interpreted by a common mind. Just like the traditional method, it gives only comparative view of impact of a performance or a player, not an absolute view in the context of winning or losing a game.
In summary, following are the aspects and calculations on which this method works:
For decades, there has been a traditional method of recording performance stats to highlight the value of any performance in Cricket and it has served the purpose, somewhat, for Traditional Cricket - Tests and ODIs. That method aims at highlighting certain aspects depending on the nature of Cricket - for example, batting average and bowling strike rates for Tests and combination of batting runs and batting strike rate and combination of wickets and bowling economy for ODIs.
T20 is a bit different in that sense. Unlike other formats of Cricket - Tests and ODIs - players get much shorter time to express their skills and it does not need a player to perform for a relatively longer period to make an impact on the game. The game changes in even just a couple of deliveries. A couple of wickets in quick succession, a maiden over, couple of under-4-runs overs, 3 successive boundaries, a quick fire 25 or 30 runs on 10 balls or even 10 in 3 balls - all of such events, most of the times, result in irreversible impact on the game.
For example, in Tests, a batsman is supposed to either score runs at all costs or don't get out, therefore, the idea of excluding the 'Not Outs' from the calculation of Batting Average looks appropriate. Similarly, the primary objective of bowling in Test Cricket is to take 20 wickets even if it comes at higher economy, so Strike Rate carries higher significance in judging the bowler than economy of his bowling.
In ODIs, a batsman's value is judged mostly by the amount of runs, 100s and 50s scored. Averages or Strike Rates don't catch the eye unless they are either too high or too low but they alone are not used to judge a batsman. In bowling, its the economy and number of wickets that takes the precedence while average and strike rates gets the same consideration as batting average and strike rate.
It all changes in T20. T20 is impact Cricket where a player has to make an impact in a shorter span and has to keep making it in successive spans to avoid getting the initial impact stand neutralized or ineffective. The batting average usually does not carry that much weightage as in Tests or ODIs as it runs scored does not consider to be having an impact unless it is with certain strike rate. In fact, scoring more runs with lower strike rate is what, at times, make it look even worse than not scoring them at all.
Then, the bowling in T20 is seen somewhere in the middle of Tests and ODIs. Like ODIs, the objective is still to restrict the opponents from scoring runs but there is no better and more efficient way of doing it than taking wickets at regular intervals like in Test Cricket. That's what gives the Economy and Bowling Strike Rate more significance while evaluating value of a performance or a player.
T20 Cricket is still evolving but it has already been played enough for some generic performance benchmarks to be set that can be applied to calculate the impact of a performance.
Batting Strike Rate of 130 and an average of 30 is what is generally considered as a benchmark for a good T20 innnings. 50s and 100s still carry its significance as scoring a 50 or a 100 in such a short span has to be considered an achievement in itself as well.
For Bowling, its the Economy of less than 8 runs per over and strike rate of 12 (2 wickets in 4 overs bowled) that can be considered as a benchmark for a good performance.
That's what gave birth to the idea to have a different kind of stats method for T20s that can take meaning of numbers closer to how a performance is interpreted by a common mind. Just like the traditional method, it gives only comparative view of impact of a performance or a player, not an absolute view in the context of winning or losing a game.
In summary, following are the aspects and calculations on which this method works:
Batting Performance Impact:
- Batting Strike Rate Benchmark : 130 runs per 100 balls
- Batting Average Benchmark : 30 runs per dismissal
- Performance Benchmark : 130 (SR) + 30 (Average) = 160
- Quality = (Strike Rate + Average) / Performance Benchmark
- Frequency = Balls Faced / Match
- Player Impact = Quality x Frequency
- 100Factor = 100s scored / matches played
- 50 Factor = 50s scored / matches played
Bowling Performance Impact:
- Economy Benchmark : 8 runs an over
- Strike Rate Benchmark : 12 (2 wickets in 4 overs)
- Performance Benchmark : 8 (Eco) x 12 (SR) = 96 [rounded off to 100 for the sake of simplicity]
- Quality = Performance Benchmark / (Economy x Strike Rate)
- Frequency = Balls Bowled / Match
- Player Impact = Quality x Frequency
- 4WFactor = 4 wickets in an innings / matches played
- 5WFactor = 5 wickets in an innings / matches played
Bowling Impact = Player Impact + (Player Impact x 5WF) + (Player Impact x 4WF/2)
Fielding / Wicket Keeping Impact:
This aspect is not considered in the calculation for the following reasons:
- Complete data not available. Generally, its only the 'successful performance' resulting in a catch, stumping or a run out that is recorded and there is no record for missed opportunities. Therefore, those stats give only one side of the picture and do not cover the cases where a player might have taken 1 catch but missed 3 opportunities in the same game.
- In T20, even wicket keepers are picked primarily for their batting skills and it is a common sight to see stand in or make shift keepers to be keeping wickets. Even in case of a specialist keeper playing a game, his impact on the game is almost always assessed on his batting performance not usually on his keeping performance.
For results of application of this method, see other posts.