Following on from our analysis looking at the comparative bowling skills in various T20 leagues across the world, here we analyse the key batting qualities that are demonstrated from competition to competition. The ever-evolving world of T20 means that emphasis is constantly on finding new ways to get one step ahead of the opposition, whether that be on an individual or team basis.
As we have already discovered in the previous article, different leagues need different areas of expertise, and so here we will delve into the same six tournaments – the Indian Premier League (IPL), Australia’s Big Bash League (BBL), the Caribbean Premier League (CPL), Pakistan Super League (PSL), Bangladesh Premier League (BPL) and England’s T20 Blast. All leagues are analysed from their initial inception, with the exception of the T20 Blast which only includes figures from the previous ten years. We have developed a Batting Index to complement our Bowling Index, once again allowing comparison and analysis between individual performances in order to highlight what, statistically, are the most important qualities to succeed in each respective league. The Index is also adjusted to be relative to the average performance of players in a given year, meaning those who performed better than the average are rewarded and those who performed below the mean were less well recognised.
Once again, as this article is based around statistical correlations between two variables, the two most important aspects to understand are positive and negative correlation. Put simply, a positive correlation is when one variable increases, so does the other; negative correlation is when one variable increases, the other decreases. The maximum value for a positive correlation is 1 – indicating that as one variable increases the other increases 100% of the time -, whilst the minimum possible value is -1, which would demonstrate that as one value increases the other decreases 100% of the time
How important is finding the boundary?
With the emphasis in the shortest form of the game on scoring runs quickly, being able to find the boundary is a non-negotiable for a modern-day batsman. In order to compare the boundary-hitting ability of all players, we have compared balls-per-boundary (BpB) against various other metrics to see its effect and importance.
When looking at the relationship between BpB and batting average, it is the CPL that has the strongest relationship with a correlative figure of -0.315 – meaning, of all the leagues, those who average higher in the CPL have a lower BpB figure – whilst the T20 Blast has the weakest association at a figure of -0.115, suggesting that there is a smaller relationship between those who average higher and the frequency at which those individuals find the boundary.
It is, therefore, probably not surprising that the CPL is still the stand-out when it comes to the link between BpB and overall runs scored, although the Blast does not remain at the bottom – as can be seen below. 
The CPL’s relationship becomes stronger here than when BpB is compared to average, progressing to -0.395, with the five other leagues also displaying a stronger correlation than the previous graph. The Blast was the biggest mover, having a correlative figure here of -0.261 – a difference of 0.146 when compared to the first graphic, pushing the BBL to the bottom instead with its figure of -0.257.
With all figures for BpB-Runs showing a greater absolute value than when comparing BpB-Average, as already mentioned, this interestingly shows that boundary hitting is more of a deciding factor in overall run scoring than it is in a player’s average.
To take a conclusive look at the importance of BpB, we can finally analyse the relationship between it and the overall Batting Index of a player. 
With the CPL’s positioning as the tournament at the top of the two illustrations we have seen, it is therefore expected for it to remain as the competition where BpB has the highest impact on Index with a correlative figure of -0.565. Following on from this, there are three leagues all with very similar figures shortly behind: PSL (-0.444), BPL (-0.434) and the Blast (-0.433). At the other end of the spectrum, the BBL is the tournament where BpB has the lowest impact on Index, collecting a correlative figure of -0.283.
Is longevity needed?
When thinking about T20 cricket, longevity is probably not the first word that comes to mind given its ebullient nature. However, time at the crease is obviously needed in order to be able to score any significant volume of runs.
If we look at the relationship between the number of dismissals in a tournament and average, it can be seen that the significance of this varies depending on the given competition.
The Blast is the competition with the clearest correlation between the two, a correlative figure of -0.442 indicating that fewer dismissals are key to having a healthier average. Conversely, there is almost no relationship in these two variables in the PSL given that its figure sits at -0.013. Between these two tournaments are the other four leagues, with the BBL being the competition who comes closest to rivalling the Blast when it comes to the importance of staying in with its figure of -0.33.
When looking at the effect of balls faced and number of innings’ batted in on Index, it is actually the Blast that now has the lowest correlation with figures of 0.573 and 0.805 respectively, suggesting that the Blast is the tournament where time at the crease is the least significant.
The BBL is the league which seemingly requires the longest periods of time spent batting in order to be successful, given that its values of 0.774 and 0.903 respectively are the highest in both of their respective categories. The CPL is the second-highest tournament for the importance of balls faced (figure of 0.743), although it drops to third when looking at the number of innings’ (0.87) as it is overtaken by the PSL (0.904).
Score highly or score quickly?
As has already been spoken about, there can be as much if not more value in T20 cricket for a 25 of 10 balls as opposed to a 50 from 50. Depending on the game situation and context, speed of scoring can be vital for a team’s acceleration throughout an innings and allowing them to capitalise on powerplays or certain match-ups.
The relationship between average and strike-rate is most prevalent in the CPL with its figure of 0.471 being the highest, edging out the BPL and IPL at 0.391 and 0.388 respectively. Meanwhile, the Blast is once again the league with the lowest figure at 0.287. Therefore, the CPL is the league where, traditionally, players with a higher average score quicker too, whilst the Blast is the competition with the biggest disparity between high scorers and quick scorers.
Moving onto the respective importance of average and strike-rate on Batting Index, we can see that it is the CPL again which is the league which demonstrates the highest importance of both metrics. 
Starting with a player’s average, the CPL’s correlative figure of 0.379 is the highest of any, 0.036 higher than the PSL in second place. There is a relatively large disparity here between the top and the bottom, with the BBL and the Blast displaying the lowest figures of 0.099 and 0.09 respectively, indicating that batting average in these two tournaments is pretty unimportant in contributing towards their overall performance. The range here is the second largest of all individual metrics’ impact towards their overall Index – behind only strike-rate, as we will now see.
Again, CPL’s figure of 0.643 is the largest of all six competitions, although all tournaments see a rise from their respective figure when looking at the effect of an average – most notably the Blast, which sees a huge rise from the lowest value for averages to third-highest for strike-rate. Its value of 0.488 is marginally ahead of the IPL’s 0.48, albeit not quite high enough to move past the PSL’s 0.567, although its increase demonstrates a much more significant weight is placed on speed of scoring than average.
The BBL remains languishing towards the bottom at 0.313, suggesting that neither average nor strike-rate are hugely important towards a batsman’s success in the tournament. However, due to the aforementioned rise here when compared to averages, this is the clearest indicator that how quickly a player scores is of more value than their average.
However, this should not be mistaken for neglecting the overall volume of runs – as this is obviously the currency that all batsmen live or die by.
The importance of run accumulation is evident throughout, with the range of data here the antithesis of the previous section in that it has the smallest range in the effect of all constituent metrics on Index. 
The highest is the CPL at 0.856, fractionally higher than the PSL with 0.853, BPL at 0.84 and BBL at 0.831. Conversely, the Blast is the league where runs have the lowest effect of all, with a correlative figure of 0.783, behind the IPL at 0.81.
Conclusion
It is interesting to identify the most important skill sets from league to league, and the varying degrees of importance in each respective competition. Whilst longevity is required in the BBL, the CPL is a tournament where the emphasis for batsmen is very much on run-scoring quickly. Each competition has its nuances and provides different challenges for batsmen – and it will be fascinating to see how these evolve in the years to come.