With his innings in the last match, Colin Munro reminded us of something that is easy to forget: he is a wonderful T20I batsman. He was the second-highest scorer in the series, and it was his 7th consecutive multi-match series where he's averaged over 30. In 6 of those 7 series, he also had a strike rate over 166.
His ability to hold his form, and hit anywhere around the park, either through the gaps or over the infield is remarkable. Especially given that the ability seems to disappear once he puts the slightly different coloured jersey in ODIs.
Compared to other batsmen who have played at least 30 T20 internationals, Munro has an average and a strike rate that matches well. He has the 13th best average in history, and of the players in the top half for averages, he has the best strike rate. That can be seen on the following graph of every player in the top half of international averages. Some notable players are coloured red and named.
It's clear that he's an elite batsman. A good way to compare players is using a statistic known as "Batting Index". This is basically the average multiplied by the strike rate then divided by 100. This statistic is useful because it increases with big and fast innings, and decreases with small and slow innings.
Here's a graph of all the top batsmen's batting index. Again some notable players have been named.
The two circles just after Munro are Kevin Pietersen and Mike Hussey. It's clear both how well Munro has been doing, and also just how far ahead of the pack Virat Kohli has been recently. Most players have a slightly higher batting index in T20 cricket than in ODI cricket, but it only tends to be about 8 to 16 points higher. They tend to score more runs in ODIs, due to taking fewer risks, but their lower strike rate brings down the batting index.
Munro's batting index in T20 is 27.75 higher than his batting index in ODI cricket. That's a massive difference. The only one with a higher difference is Aaron Finch (difference of 27.85). Graphically, it's possible to see where Munro sits compared to other players:
Apart from Finch, there's one other player who is close to Munro, and that's McCullum. Given that they are being asked to play a similar role, and most of their innings have been in similar conditions, it is an interesting comparison.
One of the promos on Radio Sport in New Zealand has been a commentator saying that "Munro has all the arrogance of McCullum, but only half the talent". That statement is a big call, and makes it worth investigating if McCullum's record was really that much better than Munro's record. The calls for McCullum to be dropped were a constant backdrop to any cricket coverage for the majority of his career. That changed in the last 2 or 3 years, but it took a long time for him to win over the general cricketing public.
McCullum started off his career while he was very young, barely out of the under-19 team, and played as a keeper who batted at number 8 or 9 for a long time at the start of his career, so it made sense to only compare their records as ODI openers.
The first graph here is their cumulative runs scored after each innings. There is no clear difference.
Next is their cumulative strike rates as an opener. Given that they have both been given the job to up the ante, and make sure there is less scoreboard pressure on Martin Guptill, Kane Williamson and Ross Taylor this is a valuable statistic.
Munro clearly scores at a faster rate, although this may be a little misleading, as there were different fielding restriction laws at the start of McCullum's opening career, and only one new ball. We know that bringing in the two new balls has seen a great increase in the scoring rates of players, and that's evident in the increase in McCullum's strike rate near the end of his career.
Combining these gets us the batting index. The following graph shows the cumulative batting index.
Munro is ahead again, but the trend is negative here, which is not surprising, as he has been going through a lean patch.
The final comparison here is one that is not done often, but is quite revealing. Consistency is something that is often desired in cricketers, but is often very rare. Very few players score more than 30 in more than half of their innings.
Any way of defining a successful innings needs to be somewhat arbitrary. Having an individual innings index of 30 to define a positive contribution seemed as good as any other value. 20(13), 30(30) or 45(67) all seem like about the border between making a positive contribution and not making one. This then allows an answer to the question "how often does each player make a positive contribution"
Again this uses the cumulative graph, to look at a similar stage in their respective careers.
The issue here is that to look at a proportion, larger sample sizes are really needed to make a sensible comparison. It looks like Munro's contributions are converging to about 40 percent, similar to McCullum's. Given that their job is a high risk/high reward one, 40 percent seems to be a fairly good result.
This leads to the question, why is Munro doing so badly in ODI cricket compared to T20 cricket, and if he's doing as well as a young McCullum, is he worth persisting with?
The first of these is an interesting question, because it cannot be answered solely statistically. What can be answered statistically is if there's any evidence that there is actually a difference, or if it's potentially just random variation. By randomly allocating his 95 limited overs innings into two groups (one of 49 and one of 46, which is the breakdown of his innings in reality) it was possible to show that only 1.2 percent of the time was there a greater difference in batting index of 27.75. This suggests that there may actually be a real difference.
Visually, that difference is evident. Munro seems to stand stiller in T20 cricket, and plays through the off-side more often. He seems more likely to play unusual shots in ODI cricket, and these probably disproportionately leads to his dismissal. The issue may be one of approach, rather than anything else. However, there are a couple of other differences. The bowlers have more time to work on plans for him in ODI cricket, and there are two new balls, so there are more opportunities to get him out with a new ball.
Whatever the issue is, it seems one that the coaches should be backing themselves to work through, rather than just discarding him. McCullum was a major factor in New Zealand's success in the 2015 World Cup, and if Munro can replicate that, it would certainly make New Zealand stronger.