Abstract
A team batting second in a limited overs match is under pressure to score the required number of runs for victory in the allotted number of overs without losing all its wickets. The bowling team has to prevent its opponents from reaching the target for victory. The objective of this study is to define methods that can be used to assess the pressure on the two teams’ batsmen and bowlers when playing the second innings of a Twenty20 or One-day match, and also to define methods to determine the best partnership and the turning point in such an innings. Methods are also defined to determine the batting and bowling performances of individual players in a specific match. These measures can be quite useful for selectors to assess how the players perform under pressure.
Introduction
In a limited overs match, played between two teams A and B (say), team A bats first for a fixed number of overs. In these overs, team A tries to score as many runs it can against the fielding and bowling of team B. Team B tries to restrict the runs of team A. At the end of the innings of team A, a “target” is set for team B, which is one run more than the runs scored by team A. This target has to be achieved by team B within the specified number of overs without losing all its wickets. In a One-day match (50 overs in each innings), one over is equivalent to only 2% of the balls available for the batting team but in Twenty20 cricket one over is equivalent to 5% of the total number of balls the batting team has to face. Thus, a slow scoring rate at the start of the innings or losing too many early wickets creates pressure for the team batting second and it becomes hard to achieve the target. In an attempt to accelerate the rate at which runs are scored, the batsmen expose themselves to the possibility of getting out because aggressive batting can lead to the fall of wickets. Avoiding this risk may result in a slower scoring rate, which makes the job difficult for the team. A high scoring over, on the other hand, makes the team’s position more comfortable. The purpose of this study is to define criteria that can be used to measure the pressure experienced by both teams and to use these measures for various purposes. The pressure on the teams can change after every ball. A dot ball (a ball from which no run is scored, normally indicated by a dot on the scorecard) or the loss of a wicket increases the pressure on the batting team. A scoring shot like a six or a four, or a productive over of 20 runs, makes the task of the batting team easier and decreases their pressure level. This study attempts to quantify the pressure on both teams in the second innings of a Twenty20 or One-day match at any given point of the innings. The pressure on team B is inversely proportional to (i) the number of balls left and (ii) the number of wickets in hand, but directly proportional to (iii) the runs that remain to be scored.
According to Paccagnelia, 1 “Pressure usually refers to the feelings an athlete has about performing in a sporting situation. It is often experienced as a compelling or constraining influence on the mind, or an urgent demand that must be met. Pressure is a feeling that is created by ourselves, when we react to particular events or situations”. The pressure is exerted by the opposing team and can lead to anxiety. According to Quinn 2 : “Performance anxiety in sports is described as a decrease in athletic performance due to too much perceived stress”. Another description is: “A critical deterioration in the execution of habitual processes as a result of an elevation in anxiety levels under perceived pressure, leading to substandard performance”. 3 Paccagnelia 1 added: “Pressure isn’t necessarily bad – it can enhance motivation, concentration and enjoyment. That feeling of stress that often accompanies a pressure situation can help keep you on your toes, ready to rise to a challenge”.
Review of literature
Cricket is a data-rich sport. A large number of papers have been published on performance measurement, decision making, and team selection. Resetting target scores in rain-truncated matches used the Duckworth/Lewis and other methods—cf. Duckworth and Lewis, 4 Jayadevan, 5 de Silva, 6 Preston and Thomas, 7 and Bhattacharya et al. 8 Some other works that were concerned with the progress of scoring in the second innings of limited overs matches are Bailey and Clarke 9 and de Silva et al. 10 Bailey and Clarke 9 attempted to predict the final score of the second innings of a One-day match while the game was in progress. They used the Duckworth–Lewis resource table at the end of each over of the second innings and tried to predict the final score of the match vis-à-vis the winner of the match. de Silva et al. 10 again used the Duckworth–Lewis resource table to estimate the magnitude of victory in One-day matches. They suggested that this can be used to break ties between teams in the points table at the end of the league stage of any tournament.
Lemmer 11 defined a performance measure PR that describes the batting progress of the team batting second in a limited overs match. In the present notation PR = CRRR × RU where CRRR denotes the current required run rate and RU denotes the percentage of resources that had already been used according to the Duckworth–Lewis 4 system. PR was based on the fact that the performance of the batting team not only depended on its required scoring rate, but also on its use of resources, i.e. wickets lost and balls already bowled. This measure was used to construct a method to measure “choking” in cricket. It was first introduced in a conference lecture. 12 See also Lemmer. 13 Shah and Shah 14 defined a “pressure index”, which can also be used to assess the team’s progress during its innings. The pressure index (PI) in Shah and Shah 14 consists of various parts based on batting performance and wickets lost. Unfortunately, it lacks motivation and some symbols are undefined.
The term “index” has a wide variety of meanings. Borrowing from the Oxford English Dictionary, we describe a pressure index as “a number indicating the relative level of pressure compared with a standard”, where the standard refers to a base or starting value. In this study it is assumed that the base value will be 1 or 100, and that the index fluctuates around this value according to the pressure exerted by the opponents.
The purpose of the present study is to define and study statistics that can be used to measure the pressure that the batting team or the bowling team experiences at any stage of the match. The pressure on the batting team is obviously determined by a combination of two factors, namely its batting performance and its ability to retain wickets. Similarly, the pressure on the bowling team is determined by its ability to take wickets and to restrict runs scoring of its opponents.
Method
Performance criteria
We start by looking at criteria that can be used to measure pressure in a cricket match. It is customary to assess the scoring process by calculating the required run rate from time to time in order to see whether the scoring rate is satisfactory. Let T be the target runs for team B. At the start of the team’s innings, the initial required run rate is IRRR = 6.T/B with B the total number of balls available. During its innings, an eye should be kept on the current required run rate CRRR where CRRR = 6.Rr/Br with Rr the number of runs still required and Br the number of balls remaining. If this is compared with the initial required run rate, IRRR, it is easy to judge whether satisfactory progress is made. The ratio
As far as bowling is concerned, two criteria can be considered. Firstly, the bowling team wants to take as many wickets as possible at a fast rate in order to weaken the batting team’s strength. As wickets fall, the team’s wicket strength deteriorates according to the number of wickets that had fallen. Instead of just counting the number of wickets down, it is important to take into account the ability of the batsmen whose wickets had been taken. When top order batsmen lose their wickets, the strength of the team is weakened more than when low order batsmen lose their wickets. In order to take this into account, the wicket weights of Lemmer 15 are used—see Table 5. We denote by ∑ wi the sum of the weights of the wickets that had fallen at any stage of the innings. When ∑ wi increases it is an indication that the team’s wicket strength decreases. Taking into account that the sum of all the wicket weights is equal to 11, the ratio SW = ∑ wi/11 reflects how far the wicket strength has deteriorated. Theoretically, the value of SW can vary between 0 (when no wicket is down) up to 0.983 (if batsman number 11, with wicket weight 0.19, is the only not out batsman). Unless both opening batsmen keep their wickets until the end of the match, the team’s wicket strength will necessarily deteriorate and its task becomes more difficult. As wickets fall, the value of SW will initially increase rapidly, but its growth will slow down when low order wickets fall. We use exp(SW) as factor in order to enlarge the effect of wickets falling and because its initial value is 1.
Secondly, the purpose of the bowling team is to prevent the batting team from reaching the target score before its resources are depleted. The Duckworth–Lewis full table for Twenty20 matches gives the percentage of resources left to the batting team at the end of each ball depending on the number of wickets lost—cf. Bhattacharya et al. 8 Subtracting the value from 100 gives RU, which indicates the percentage of resources used. This depends on the number of overs team B has batted and the number of wickets it has lost. Thus RU can be used as an alternative to SW and the change in pressure due to resources used can be quantified by exp(RU/100).
Pressure indices
Shah and Shah
14
defined a pressure index as
No motivation was given for their formula and the factor Wk.Wt was not defined. After obtaining the values of Wk.Wt from them, it was possible to calculate PI. The starting value of PI is always 100 and its value will normally fluctuate. We have calculated PI for various matches. It was found that in many cases the value of PI decreased when a wicket went down and the number of runs scored was below the required run rate, which is totally unrealistic. PI is not considered further in this study.
In the construction of pressure indices for batting and bowling, the criteria given in the previous section will be used in the best possible way. Firstly, the definitions of pressure indices for the batting team and their applications are discussed. Thereafter, a pressure index is defined for the bowling team.
Pressure indices for batting
Definitions
In a limited overs match, the batting team has to reach the target before depleting its resources by using the balls bowled to it and losing all its wickets. The challenge to the team thus consists of two parts, namely to score the runs and not to deplete its resources before reaching the target. In the construction of a pressure index, it is important to note that the pressure will go down if the batting progress is good AND if wickets/resources are kept until the target has been reached—not the one OR the other. Therefore, the measure should be the product of the two factors, as in the definition of PR of Lemmer. 11 Two methods are used to quantify the use of resources, namely the way wickets are lost and also by using the Duckworth–Lewis resources.
The first pressure index is defined as
PI1 is sensitive for wickets falling, but not for balls used, whereas PI2 depends on all the resources used.
At the start of the second team’s innings both pressure indices are equal to 1 and will increase or decrease or fluctuate as the match progresses. At the end of the match, if team B wins, CI becomes 0 and therefore also PI1 and PI2.
Functioning of the pressure indices
To understand how the indices work they are applied in a match situation. A Twenty20 international match of the recent past with lots of ups and downs in the second innings is an ideal one to explain the working of the indices. The second Twenty20 match of Pakistan versus Sri Lanka, played on 1 August 2015, at the Premadasa Stadium, Colombo, is considered—cf. Cricinfo.
16
Sri Lanka batted first and scored 172/7 in 20 overs. The target for Pakistan was 173. The target was attained by them for the loss of 9 wickets with 4 balls to spare. The initial required run rate (IRRR) for Pakistan was 8.65 per over, which was quite high. The ball-by-ball values of the pressure indices, i.e. both PI1 and PI2, are given in Table 6. The graphical representation of the same can be seen in Figure 1. The pressure increased almost consistently until a six was hit from the 98th ball. In Table 6, it can be seen that the pressure was largest in the 97th ball and that the pressure decreased rapidly thereafter due to good scoring.
The pressure index graph for the Pakistan innings of the 449th International Twenty20 match.
Pressure index values for different events in the second innings.
Pressure index for batting partnerships.
Values of pressure indices at the end of each over of the Pakistan innings.
Both graphs of PI1 and PI2 depict the situation appropriately with the pressure on Pakistan increasing at the fall of a wicket and the pressure decreasing after an over where many runs were scored. Table 1 provides the increases in the values of PI1 and PI2 at different situations of the match. The increase in both the indices after high and low scoring overs and after the fall of wickets provides interesting insight into the indices. It is seen that generally the change in the index PI1 is less than in PI2 both in the case of low and high scoring overs. Thus, PI2 seems to be more sensitive than PI1 in this regard. However, in the case of the fall of wickets PI1 is more sensitive compared to PI2 as can be seen from Table 1. This is obvious, as the factor CI is common to both PI1 and PI2. The only difference between PI1 and PI2 is in their exponents. The exponent changes after every ball in case of PI2 because of a change in the value of RU, but the exponent of PI1 changes only at the fall of a wicket. When a wicket falls, the task of the batting team becomes markedly more difficult because the new batsman has to play himself in and the scoring rate normally drops. PI1 reflects this very well. But during a partnership PI2 is better suited than PI1 to reflect the use of resources. It is therefore logical to use the average of PI1 and PI2 as measure for the pressure index of the batting team. This is defined as
The values of PI3 were computed at the end of each over and are shown in Figure 2. Plotting at the end of each over, instead of ball-by-ball, makes the pressure curve smoother.
The pressure curve based on the pressure index (PI3) values at the end of each over.
The pressure indices can be used for a number of purposes. Some of these are highlighted here.
Finding the best partnership of an innings
The most successful partnership of the match can be identified as the one in which the pressure on team B was decreased to the largest extent.
The exercise shows (see Table 2) that the performance of I Wasim and A Ali as pair has decreased the pressure on the batting team the most. The negative value of the increase in pressure index PI3 indicates the lowering of the pressure on Pakistan due to this pair of batsmen.
Finding the turning point of the match
The pressure curve will sometimes indicate a clear turning point of the match if team B wins, as can be seen in Figure 2. The curve shows that Pakistan lost wickets at regular intervals and the pressure level kept on increasing. But things changed in the 17th over, where 21 runs were scored. After a six from the second ball the pressure decreased and the trend continued in the remaining overs—cf. Table 6. Thus, the 97th ball (the first of the 17th over) of the Pakistan innings can be considered as the turning point of the match. In some matches, there can be more than one possible turning point. In such a case, the peak or trough, which is closest to the end of the match, may be considered as the ultimate turning point.
Measuring batting performance
The batting performance of the players in a single innings can be compared in terms of runs scored or/and strike rate. But here we propose a new batting performance measure in a single innings.
Ave(PI3) denotes the average pressure of the entire innings. PI3,
i
denotes the pressure level at the end of the ith ball of the second innings of the match. Rij denotes the runs scored by batsman j in the ith ball of the match. Then, the runs scored in the ith ball is transformed to the adjusted runs scored (Rij*) using the following relation
That is, the adjusted runs scored in the ith ball is the actual runs scored multiplied by the ratio of the pressure index at the end of the previous ball to the average pressure level of the innings. Summing up all the adjusted runs scored by a batsman (jth batsman, say) renders his adjusted score. The adjusted score is a function of the actual runs scored and the pressure level under which these runs were scored. We call this his batting contribution
Batting and bowling performance values based on pressure indices.
Wicket weights of different batting positions as in Lemmer. 15
The ball-by-ball calculation of the values of pressure indices.
Pressure index for bowling
Definition and functioning
If the batting team succeeds to decrease the value of CI, the value of its inverse 1/CI will increase and also the pressure on the bowling team. In order to lower the pressure on the bowling team, it will help if wickets are taken at a fast rate, i.e. the value of ∑ wi must increase rapidly. The ratio (11 – ∑wi)/11 reflects the decrease in resources due to wickets being taken, and therefore a decrease in pressure on the bowling team. However, as resources are used the pressure on the bowling team will increase, especially if wickets are not taken, so the factor exp(RU/100) must also be included. By using the average of these two counteracting factors, the sudden effect of a wicket falling as well as the depletion of overs is taken into account. The bowling pressure index is defined as
The starting value of BI will always be 1.
The functioning of BI is illustrated by using the same data set as before, namely the second Twenty20 match of Pakistan versus Sri Lanka, played on 1 August 2015 (see Table 3).
When a wicket falls, the value of BI should normally decrease, but the number of runs scored in that over is also of importance. In over number 19, fourteen runs were scored and two wickets were taken. The joint weight of these two low order wickets was so small that the value of BI increased substantially despite two wickets falling, which was quite understandable in the context of the match situation. It must be kept in mind that if CI decreases, BI should normally increase. BI and CI are not mirror images of each other, but they will generally move in opposite directions.
Measuring bowling performance
The pressure index PI3 can be used to define a measure of bowling performance because it reflects the pressure exerted on the batting team by the bowling team. The difference Iij between the end and starting values of PI3 in the ith over bowled by the jth bowler indicates the increase in pressure on the batting team created while bowler j bowled his ith over. The average increase in pressure created while bowler j was bowling is given by
Table 4 shows that the best bowling performance amongst the Sri Lankan bowlers was by TAM Siriwardana followed by B Fernando. The best batting performance amongst the Pakistani batsmen was Anwar Ali followed by Shahid Afridi.
Discussion
The methods defined here are equally applicable and valid in One-day matches. The indices were calculated per over for many matches and the results were similar to those of Twenty20 matches. For partnership calculations it is necessary to use ball-by-ball figures only for the overs concerned.
The pressure indices developed in this paper reflect how a team batting second, chases the target, and how it reacts to the changing match situations like tight bowling or the fall of wickets. There is obviously scope for improvement. One can develop player-specific weights and include these in the index instead of wi, where i refers to the specific batsman and not to the batting order. The measures in this study are formally based on match statistics. Factors of a physical and psychological nature are also very important and it can be a challenge to take these into account too.
Some applications of the pressure indices were addressed in this paper. If the pressure indices of a team are studied for several matches it can help to identify batsmen who perform well in partnerships and using this to change the batting order, and also to study performances in power-plays. Studying the pressure curves of the opposing team can help to decide on a counter strategy. Future researchers are also expected to find several other applications of the pressure indices.
An interesting challenge for future research is to examine to what extent the methods of this study can be applied or modified for use in the first innings of limited overs matches. A possible starting point can be to use the average first innings score on the specific field to determine the “target score”.
Conclusion
The approach of Lemmer11,12 of working with the product of performance measures has found various applications in the form of pressure indices for batting and bowling. It was shown how various aspects, like partnerships, turning points, and individual performances in a match, can be calculated and illustrated. It is hoped that these methods will be useful for practitioners. The availability of computers and other electronic media can be used to make cricket viewing even more enjoyable than before.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
