Australia's conversion problem

In two-and-a-half Tests of the ongoing three-match series between Australia and West Indies, one of the most talked-about aspects has been the Australians' propensity to get half-centuries, threaten a three-figure score, and then contrive a dismissal before getting there. So far Australia have managed 15 scores of 50 or more, but the highest among them has been 99, by Simon Katich in Perth. There have been two other scores in the 90s, and four in the 80s, even as West Indies have gone ahead and slammed four centuries. All these fifties have helped Australia amass the second-highest total not to include a century - just four short of the record - but this is also the most half-centuries they've scored in a series without getting a hundred.

Old fans of Australia-West Indies encounters will perhaps remember another similar series - in the tied-Test one of 1960-61, Australia managed 21 fifty-plus scores, but the only one to go ahead and get a hundred was Norman O'Neill, who scored 181 in that memorable tied game. The next highest was Bob Simpson, who twice scored 92. (Click here for a full list of such series for Australia.)

These numbers are all the more surprising since Australians aren't usually the sort to fritter away opportunities to score centuries. (Perhaps they are making up for their stats in the 2009 Ashes, when they scored eight hundreds and yet ended up on the losing side.)

Overall in this decade, Australia have scored more tons than any other side - they've played 14 fewer Tests than England, but made 36 more centuries, which is a fairly significant difference. Not only have they scored more tons, they also have a better conversion ratio of fifties to hundreds than any other side: they've notched up 276 half-centuries and 174 hundreds, a ratio of 1.59. Only three other teams have ratios of less than two, while New Zealand are the worst of the top teams, only converting one out of every four fifties into hundreds.

Australia's stats are also unusual since their conversion rate overseas is better than that at home. For batsmen from most other sides, familiarity with home conditions means they're usually able to kick on and convert fifties into hundreds more easily in their own backyards than in unfamiliar conditions, but that doesn't apply for the Australians. (It doesn't for New Zealand either.) Australia's batsmen have converted only 90 out of 246 fifty-plus scores into centuries at home, while overseas the ratio improves quite significantly, with 80 hundreds and 115 half-centuries.

For some of the other teams, the difference in ratios is significant - South Africa's increases from 1.68 to 2.29 when they travel, England's from 1.78 to 2.61, while for West Indies it worsens from 1.95 to 3.05. The bowler-friendly conditions in New Zealand means their batsmen improve their conversions when they travel, though even then their ratio is quite poor.

Going by the data for this decade, it turns out that West Indies is one of the easiest opposition teams for batsmen to convert starts into big scores against. Of the 367 fifty-plus scores made against West Indies, 131 have been centuries, which is a better ratio than against every other opposition team except Bangladesh.

Australia, on the other hand, has been the toughest side for batsmen to convert their starts against, thanks to their varied and penetrative bowling attack through most of the decade. Only 83 out of 352 fifty-plus scores against Australia have been converted into centuries, a 50-to-100 ratio of 3.24. In this series, though, West Indies have scored four centuries and nine fifties, which is a better conversion than most other teams have managed against them.

Among batsmen who've scored at least 30 fifty-plus scores in this decade, only four have scored more hundreds than fifties, which gives them a 50-to-100 ratio of less than one - Brian Lara leads the way with 21 tons and 19 fifties, while Kevin Pietersen, Andrew Strauss and Mohammad Yousuf follow closely. Two other batsmen - Matthew Hayden and Michael Vaughan - scored an equal number of hundreds and fifties. Ricky Ponting has a very good conversion rate too, with 32 hundreds and 39 fifties, though Virender Sehwag, Mahela Jayawardene and Justin Langer have all done slightly better.

At the other end of the scale is Andrew Strauss, with only five centuries and 26 fifties. That's understandable due to his batting position, but there no such explanation for Stephen Fleming's poor conversion - out of 30 scores of 50 or more, only seven were converted into hundreds. Chris Gayle's conversion has improved with his two centuries in Australia, but his overall rate for the decade is still pretty disappointing - the added responsibility of leading the team will probably see an improvement in the ratio. If he can marry that responsibility with the kind of astonishing power-hitting he displayed in Perth on a regular basis, West Indies cricket and fans all over the world will be well served.