It’s been nearly three years since international Twenty20 cricket kicked off in earnest, with the 2007 World Twenty20.  And over five years have passed since the very first match, a trans-Tasman encounter in February 2005.  In that time, which teams have adjusted well to the 20-over game?  And which ones are still struggling to understand the format?

One thing is clear, even without looking at the data.  Twenty20 levels the playing field — with the shorter matches, it’s easier for a Zimbabwe to surprise a team like Australia.  But, as is my wont, I ended up running the numbers to compare a team’s ODI batting performance from 2006 to 2009, with its batting performance in Twenty20 matches over the same period.

The Duckworth-Lewis system comes in handy here.  It provides a proven way to judge what the 20-over equivalent of a particular 50-over score is.  The magic number is 58.6% (see this post for more info on D-L).  That is, in a T20 innings, a team has 58.6% of the resources it has in a 50-over innings.  That means that an ODI score of 300 is roughly equivalent to a Twenty20 score around 180, which sits well with my intuition.  We can look at the equivalent Twenty20 scores for some ODI teams, and then compare to that team’s actual Twenty20 scores.

Overall, every team except India exceeds the median of the predicted T20 range — perhaps there’s something systematic about D-L underestimating the Twenty20 scores.  Maybe the ODI model doesn’t map well to the T20 format.  Or maybe Twenty20 specialists like Kieron Pollard are adapting to the format better than the ODI regulars.

Twenty20 has been a boost especially to the weaker ODI teams (England, West Indies).  Both of them comfortably surpass the Duckworth-Lewis prediction in T20s.  If you have any explanations for this, please post them in the comments.

Two possibilities I can think of:

1. Duckworth-Lewis is just underestimating the prediction.  One big thing the system doesn’t take into account is the strength of individual players.  In a 20-over match, a single innings from a Gayle or a Pietersen can take the team to a good score, whereas ODI are slightly more of a team effort.
2. Perhaps it’s just that the styles of batsmen like Pollard are suited to the wham-bam game, and can’t easily be adapted to play a 50 or 100-ball innings.  This would undermine my methodology of predicting Twenty20 scores from ODI data.

Any cricket fan will tell you that a good-length ball outside the leg-stump will go for more runs than a good length ball just outside the off-stump.  But how many more runs, on average?  That’s where you need some real data to answer the question.  So, in keeping with the theme of this blog, let’s try to quantify scoring & wicket-taking by area of the pitch in Twenty20 matches.

First, let’s look at a bowler’s line and length.  Obviously, this will differ based on whether the batsman and bowler are right or left handed, and whether the bowler is a pace bowler or a spinner.  The handedness of the batsman is accounted for by making the pitch locations relative to the batsman’s off-stump.  The pitch map below shows exactly where pace bowlers land their deliveries.

The totals in the margins indicate that 73% of balls are bowled in the channel outside off stump, and nearly a quarter of balls are bowled short of a good length.  Now let’s look at how fruitful each of these delivery areas is.  Shown on the pitch maps below are the strike rates of batsmen (runs/ball) for balls pitching in that area.

We can quantify the age-old cricketing wisdom that line & length are rewarded.  Good length balls just outside the off-stump go for only about 7 runs per over (a decent economy rate in Twenty20 matches), while fuller balls are punished at over 9 runs an over.  Similarly, if the bowler strays onto the stumps, the easy on-side runs come at about 9 per over.

The data used to produce the above charts includes all Twenty20 internationals from June to November 2009, plus the 2009 Twenty20 Champions League.  The balls include approximately 4800 balls bowled by fast and medium-fast bowlers.  These pitch maps only include data on right-arm pace bowlers.  Data on left-armers and spinners may appear in a future post.