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BBL Official Player Rankings: How they work

Formula devised to rank the competition's top batters, bowlers and allrounders

With the arrival of the fifth KFC Big Bash League season comes the introduction of the Official BBL Player Rankings.

The Rankings, devised by esteemed Bond University Professor Steven Stern – the man who also lends his name to the Duckworth-Lewis-Stern method used for recalculating rain-affected run chase targets – with Cricket Australia, separates batters, bowlers and allrounders.

The system uses performances from both current and past Big Bash matches, weighted on a sliding scale from the three most recent seasons, with BBL|05 games to carry a full weighting in order to provide the most accurate, up-to-date measure of player performance.

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Professor Stern formulated the Official Rankings system for bigbash.com.au with Cricket Australia in the build-up to the season and explained that the concept is largely based around the comparative impacts of each individual player in a match.

"It's an aggregate measure, based on total performance of players over the games they've played, so there will be some upping and downing through the season as players get more games," Stern told bigbash.com.au.

"The most straightforward way to explain it is, in each game, suppose we took a player's actual performance out, and substituted in for it what the average of all the other players in the game would have produced in his place. How much difference would that make?

"Basically each player gets the difference – positive or negative – between what they actually did and what the average of the other players would have been expected to do, if they had played the same deliveries in the match.

"That way you're allowing the performances of the players themselves to tell you what the average conditions are, and if you outcompete the other players in terms of what they would have done in your place, then you get a positive component to your aggregate for the season, and if not, you get a negative. In that way, players will go up or down after each match in which they play."

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Stern said the notion of an allrounder in T20 cricket provided an interesting challenge in formulating an algorithm that accurately reflected all-round performance, with the quick-fire nature of the shortened format often resulting in matches decided by small, yet significant, contributions.

Consequently, this adds to the likelihood of tail-end batsmen or part-time bowlers playing a decisive role in a match, thus increasing their aggregate in the Rankings system.

As such, all players were considered as potential allrounders, with the algorithm then refining the list by rewarding players performing well in both disciplines.

"Basically in order to be considered an allrounder for the Rankings, all you have to do is make an overall positive contribution for both batting and bowling," Stern explained.

"However, my personal view is, if someone is just on the border of contributing positively versus negatively for one discipline, they're probably not performing in an all-round manner.

"On that note, if you look at the initial allrounder list, you might not consider some of those players to be allrounders, but those players happen to currently be providing positive contributions in both disciplines.

"To limit the allrounder Ranking exclusively to players who already have that 'allrounder' tag is somewhat arbitrary, because who decides whether a guy is good enough – or not good enough – in both skills to be judged in that way?

"And that's the whole point of these Rankings – they're objective and performance-based.

"That being the case, though, the system is designed to give preference to those who are evenly contributing in both disciplines.

"So for example, if a player has a rating of 19.5 as a batsman and 0.5 as a bowler, well technically they count as an allrounder, but if someone else has ratings of 10.0 in both disciplines, they are clearly the better allrounder and the system will reflect that.

"As the season progresses, I strongly suspect we'll see the players with the more even contributions rise to the top of that ranking."

Throughout BBL|05, bigbash.com.au will reveal regular updates for the Top 10 batters and bowlers, and the Top five allrounders.