Hit or hope
Who is the most valuable T20 batter in Australian women's cricket?
Welcome to the 10th edition of Plot the Ball — a newsletter where I offer data-driven answers to interesting questions I have about the world of sport.
This month — after following along as the eighth season of the Women’s Big Bash League has progressed in Australia — I’ve been thinking about batting in T20 cricket, and wondering which of Australia’s many star names stands out most in this format.
This will be last edition of Plot the Ball for 2022. The newsletter — in a revised format — will be back in your inboxes in January of next year.
Who is the most valuable T20 batter in Australian women’s cricket?
Today’s WBBL final in Sydney sees a team led by one of the faces of the last decade of Australian women’s cricket take on another whose captain may just be its future.
Sydney Sixers captain Ellyse Perry — an all-rounder in almost every sense — needs little introduction to cricket fans outside of her home country. Tahlia McGrath, on the other hand, is probably less familiar.
Such is the tear that Adelaide Strikers captain McGrath has been on in international T20 cricket — leading her country’s charge in recent home series against India and England, as well as at the Commonwealth Games — that Perry has not played a game for Australia in the format since October last year.
A simple case, you might think, of a ‘changing of the guard’ moment at the top of Australia’s T20 pecking order: one player, aging out of their prime and no longer the force they once were, replaced by another approaching the likely peak of their powers.
But for all Perry’s excellence across formats since her teenage years — and McGrath’s superlative 12 months in green and gold — the story is more complicated than that.
While both Perry and McGrath — when injury permits — offer front-line bowling options to their teams, in T20 the extent of an individual’s influence as part of the fielding side is limited by the 24-ball cap imposed on each bowler.
With bat in hand, there is no such limitation in place — and thus it’s in this facet of the game that elite T20 cricketers tend to truly differentiate themselves.
And data from the WBBL since its inception in 2015 — which presents a more comprehensive picture of individuals’ performance at the top level than international cricket does1 — suggests that Perry’s status as an elite performer with the bat in T20 cricket is certainly up for debate.
While there are no limitations on how many balls of an innings a single batter can utilise in T20s, the overall length of a team’s innings — 120 balls — of course remains as a constraint.
This makes the format much more about efficiency than the other, longer types of cricket in which accumulation and volume are prized.
As a consequence, many ‘traditional’ players like Steve Smith and Kane Williamson2 are simply less effective in T20 than they are in 50-over and first class cricket — and it is arguable that Perry falls into this category as a batter too.
Many more complex models of T20 efficiency exist, but a basic one to grasp is this.
Consider the number of balls faced by a batter in a given innings, and the number of runs they score off those balls. Then consider all of the other deliveries faced in the same game by other players, and how many runs are scored off those.
The difference between the batter’s per-ball run-scoring rate and the scoring rate of all other players in a game gives you a sense of how efficiently they have used up their team’s resources, given the conditions3 in which they were batting.
As a further step, taking that difference in scoring rate and multiplying it by the number of balls a batter has faced quantifies how much more or less than an ‘average’ player they have contributed across an innings, given the resources they were allocated.
Finally, performing this exercise for every game in a season — and every season in the history of a competition4 — allows you to estimate roughly how much more or less than average a batter has contributed over an entire career in the T20 format.
In fact, such analysis paints neither Perry nor McGrath’s historic contributions with the bat in the WBBL in a positive light — and reveals that there is perhaps only one Australian player who can truly be said to be an elite T20 operator.
As the table above shows, over the history of the WBBL it is Perry’s Sixers teammate Alyssa Healy who has contributed more runs per innings above expectation (+4.8) than any other active Australian player.
What’s more, she does so while using up considerably fewer of her team’s deliveries (19.4 per innings) than Meg Lanning and Beth Mooney — the other two elite Australian T20 batters based on this ‘runs vs. expectation’ metric — do.
Even after broadening out the criteria to include less experienced Australian players and top overseas stars, Healy’s per-ball efficiency stands out.
With Lanning taking an extended break from cricket, the wicketkeeper has assumed the role of national team captain ahead of their series in India next month.
And — although she has recently suffered a lean run of scores in T20Is — Healy will be backing her 20-over pedigree and hoping to cement her position as the best short-format batter in the women’s game in Australia as she leads the team on tour for the first time.
Strikers captain McGrath has also been elevated to the position of vice-captain for the upcoming series.
For the all-rounder, however, the situation is almost the inverse of Healy’s. As she enters her prime, McGrath will ultimately be looking to carry her elite performance at international T20 level so far back into future WBBL campaigns for the Strikers.
While it’s Perry’s position in the national team that she is likely to take over, it is Healy’s approach to short-format batting that McGrath should be looking to emulate if she wants to dominate the Australian domestic scene in years to come too.
In T20, after all, efficiency is the name of the game.
Adam Burnett of cricket.com.au on Alyssa Healy’s personal development during more than a decade at the top and Tahlia McGrath’s 2021 on and off the field
Melinda Farrell of The Cricket Monthly on Healy’s technical development since 2017
Laura Jolly of cricket.com.au on McGrath’s form in the 50-over format ahead of the World Cup earlier this year
You can find the code for this piece on GitHub here
As with last month’s newsletter, I was thinking again about how to use repetition while putting this piece together — in a number of different ways. Last month, I experimented with repeating a title across two separate charts to reinforce a point, and I’ve done that again here as I thought it was effective. The scatter plot above is also similar to one of the types of chart I used in my analysis of Rory McIlroy’s performance a couple of months ago, and I was thinking about the importance of presenting your audience with similar types of data in formats that are consistent across pieces too.
I also used repetition across both graphics in this piece (and in the copy) to attempt to explain clearly the ‘runs' vs. expectation’ metric I devised to analyse batting performance. The explanation is trailed first in the text, before being included in brief at the top of the first graphic and in a less prominent position at the bottom of the second. (As an aside, I decided to err on the side of simplicity rather than complexity and accuracy when coming up with this metric — partly to save myself a bit of work, but mainly to ensure it was as clear as possible to a non-specialist audience. While it has some significant drawbacks as a measure, for the purpose of this high-level analysis I think it’s a trade-off worth making.)
Both because of the limited sample of data available, and because players from Australia — clearly the women’s game’s dominant force — cannot face each other in international competition.
They continue to approach T20 as a ‘batting’ game rather than a ‘hitting’ game, as it was so neatly framed by the 81 All Out podcast recently.
More accurately, given some of the conditions. In T20, weather, pitch and boundary conditions should generally be comparable for both teams in a given match; the quality of bowling faced will vary between teams, while the constraints placed on the bowling team in the form of fielding restrictions will vary within teams depending on when in the innings each batter faced their deliveries.
The analysis above includes all completed WBBL games up to the beginning of the 2022 playoffs.