Arguing the toss

Josh Pinn on Twitter asked last night:

This is a good question, and one that is easy to answer with my dataset. In this post I’ll look at how the fashion in men’s T20 cricket has shifted towards teams preferring to bowl first, and also whether there is evidence that this works.

Firstly, let’s take a look at how often teams choose to bowl when they win the toss in the Big Bash League.

toss4.png

It’s a dramatic shift. Up until 2011/12, it was rare for teams to choose to bowl. Around 20% took the option in 2007/8 and 2008/9, but in 2009/10 a team chose to bowl first in only one out of 16 matches. We came closer to parity in 2012/13, but only a quarter chose to do so in 2013/14. In 2014/15 the team who won the toss chose to bowl in exactly half of the matches. Last season a small majority of matches saw teams choosing to bowl.

In the first five matches of this season, every team has chosen to bowl.

(It’s worth noting that I’ve excluded matches affected by rain for some of the later analysis, which means these numbers don’t cover every single match).

So let’s look at the same analysis but for all men’s Twenty20 cricket globally, broken down by year:

toss1.png

The trend is less dramatic – we don’t see a strong preference for batting first before 2012, but it is a clear favourite. In 2013 bowling first became the slight preference, and in 2016 so far almost 64% of teams chose to bowl first.

It’s also worth noting that we don’t have data on who won the toss for many games. This is why I can’t do a similar analysis for women’s cricket, since we don’t have toss information for domestic cricket in Australia prior to the first season of the WBBL. For what it’s worth, only three out of 55 matches in WBBL01 saw the team choose to bowl, but so far this season the team winning the toss has chosen to bowl in 6 out of 14 matches.

So why have teams been opting to bowl first? I won’t try to cover every possible explanation, but let’s start with something simple.

Firstly, does winning the toss give a team an advantage in terms of winning, ignoring all other factors?

toss3.png

It’s very marginal, but it exists in most years. 51.8% of teams winning the toss in 2016 have gone on to win the match. Teams winning the toss have won a majority of matches in all years except 2008 (narrow majority of losses), 2012 (solid majority of teams lost) and 2014 (both losses and wins made up a minority, with the rest being ties). So winning the toss appears to give a slight edge.

So what do you do with it? This next chart is the same as the chart above, but it breaks down the results based on the decision the team made after winning the toss:

toss2.png

In both 2015 and 2016, teams choosing to bowl won a majority of the time, and teams choosing to bat lost a majority of the time. This trend hasn’t always existed – from 2009 to 2011, it appears that teams did better when they chose to bat.

Finally, I wanted to look at whether there is a general tendency for a team batting first or second to win, taking out the question of whether there is extra information that the team winning the toss might be using to judge whether batting first or second is in their best interest. This graph shows the number of matches won by the teams batting first or second:

toss6.png

One shouldn’t overestimate the gap, but teams batting second have tended to win in a majority of matches in most recent years.

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