Trent Boult and Tim Southee – among the great new-ball pairs in Test cricket

Five of their top six combined hauls in a Test (and 11 of their top 13) have come in home conditions, which isn’t a surprise given that both are primarily swing bowlers who don’t have extreme pace. What they do have in abundance, though, is the ability to swing the ball both ways and exploit favourable conditions. In innings when they have shared the first new ball in home conditions, Boult and Southee have a combined tally of 256 wickets at an average of 24.3. [Individually, again, the numbers are similar for the two: 131 wickets at 23.96 for Boult, and 125 at 24.65 for Southee.]

Over the eight-and-a-half years that Boult and Southee have been playing together, New Zealand’s Test results have been significantly better in matches where both have played, compared to matches where either one – or neither – has played. The table below lists out those three situations: when both have played, New Zealand have a 28-15 win-loss record; when one of the two has played, it reduces to 3-9; in the five Tests neither has played, New Zealand have lost three and drawn two.

Combining the instances when only one of the two bowlers played a Test or when neither of them were in the XI (since they first started playing together), New Zealand have a 3-12 record in 21 Tests. Compare that with their 28-15 win-loss record when they have both played, and it’s obvious that the difference is huge. The impact value of 7.46 is obtained by dividing the win-loss ratio when both played (1.87) with the ratio in the other 21 Tests (0.25). This value indicates that New Zealand’s Test results have shown a seven-fold improvement when both Boult and Southee have been a part of the team.ESPNcricinfo LtdObviously, that doesn’t mean that the entire difference can be attributed to Boult and Southee. There are other factors involved, including the performances of the batsmen and the other bowlers. Plus, Boult and Southee tend to play more often than not in home games, where conditions are generally in favour of New Zealand. [At home, New Zealand have an 18-2 record with these two playing, and 2-2 otherwise; in away and neutral venues, the corresponding numbers are 10-13 and 1-10.]The numbers above do say that New Zealand’s results lift considerably when Boult and Southee are in the XI. Comparing that impact value with other pairs of bowlers (those with at least 300 wickets playing together for their country, with each bowler contributing at least 40%, and with at least 10 Tests during their career span when they didn’t play together), only one pair – R Ashwin and Ravindra Jadeja – have a bigger difference in win-loss ratios. That is because they tend to play together at home, where conditions are generally spin-friendly; overseas, only one of them typically plays. Compared to everyone else, though, Boult and Southee seem to have had a greater impact on team results, which indicates just how vital they have been to New Zealand’s Test fortunes.