Steven Smith, the world's best batsman. In England the reaction to Smith's ascent to the top of the ICC Test batting rankings has been a slightly peculiar Venn diagram of confusion and admiration. While Smith's position is the England team's main point of interest in the rankings right now, they should also pay attention to those directly below him.

AB de Villiers and Kumar Sangakkara are second and third in the Test rankings; they are also first and second in the ODI rankings. Both have had an on-off relationship with the wicketkeeping gloves, and England might study their careers in an attempt to maximise the astonishing talent of Jos Buttler over the next decade.

Buttler's potential as a batsman is almost infinite, and as such there is a persuasive argument that he should be eased away from wicketkeeping in the next year or two so that England can discover just how good he can be. He is a perfectly decent wicketkeeper, and is performing superbly with the bat in all forms of the game for England at the moment. But there is the nagging thought that, by saving the enormous mental and physical energy a wicketkeeper exerts, he could achieve almost anything.

English cricket thinks more than other countries about the effect of other jobs, particularly captaincy and wicketkeeping, on a batsman's output. The latter is a consequence of the career of Alec Stewart, who was routinely messed around by the selectors in the mid-1990s. When he played as a batsman, usually opening, he was world-class and had a Test average of 47 in a golden age of fast bowling; as a keeper that dropped to 35, almost Graeme Hick territory.

Sangakkara and de Villiers have given up the gloves at different stages of their careers; that was partly because of captaincy, which isn't an issue for Buttler at this stage, though it serves the same essential purpose: clearing the mind to focus on what is really important. It is good for all young cricketers to have one more than one string to their bow, but sometimes a player reaches a level where you have to focus on the best bit, not the other pieces. The greats should not be utility men.

Buttler is nowhere near de Villiers or Sangakkara yet, but he could get there and that alone is eye-popping in a country that has produced scarcely any all-time great cricketers in the last 50 years. At the age of 24, he has already scored England's two fastest ODI centuries. He averages 53 in his short Test career, yet it feels like he has barely played an innings of note. The way in which he effortlessly underhits straight sixes in particular suggests a ridiculous talent.

"It is good for all young cricketers to have one more than one string to their bow, but sometimes a player reaches a level where you have to focus on the best bit, not the other pieces"

Those two hundreds are the only ones he has scored for England in any form - the reason he scored them was because of his extraordinary rate of scoring rather than the opportunities afforded by his position in the batting order. Taking the gloves off Buttler would allow him to eventually move up and play longer innings, perhaps at No. 4 or No. 5, a role that would suit him as Test batting goes through the gears in a post-McCullum world. But even if he remains a finisher in one-day cricket and lower middle-order counterattacker in Test cricket, there is every chance he will benefit from narrowing his focus.

The statistics - don't call it data, not any more - support that view, though maybe not to the extent you might think. The original hypothesis of this article was that Buttler should immediately give up the one-day gloves, which could go to Sam Billings or Jonny Bairstow, with a view to doing the same in Test cricket within a year or so, perhaps when Ian Bell retires or is dropped. But the evidence of wicketkeeper-batsmen suggests wearing the gloves does not make that much difference in one-day cricket as compared to Tests. That is logical enough: you keep for longer in Test matches, there is not the same structure or routine for which you can prepare, and the cricket is more intense, so the demands on the body and mind are greater.

In 50-over cricket, there is not much difference in the records of the main keeper-batsmen with and without the gloves. Indeed de Villiers and Sangakkara both average significantly more as keepers, although that is partly explained by the fact that many of their games as batsmen came early in their careers, before they had reached their peak. Even so, Sangakkara made four consecutive one-day centuries at the World Cup, and you could make a good case for MS Dhoni - who has kept in all his ODIs - and de Villiers being the greatest ever finisher and death-hitter respectively. The same is true of Adam Gilchrist, the greatest wicketkeeper-batsman of all, who kept throughout his Test career and averaged 48.

Jonny Bairstow takes a ball as wicketkeeper Getty Images

They are all freaks. Dhoni's heart rate under pressure is that of a medical marvel, Gilchrist changed cricket forever and de Villiers has so much talent that he would probably score big runs if you made him bat with wicketkeeping gloves on. Buttler is a freak too, but the others might have been even better without the pressure of keeping. Even allowing for the fact that Gilchrist transcended statistics to some extent, an average of 48, in an era where tens of players ended their career in the 50s, arguably does not reflect his talent.

Sangakkara undeniably benefitted from playing as a batsman in Test cricket. He was affronted when the selectors took the gloves from him seven years ago, but soon the evidence of their wisdom became undeniable. "I protested," he told ESPNcricinfo in 2010. "I would still like to protest, but statistics tell me the decision was the right one." He averages a whopping 69 in 84 matches as a Test batsman, as against 40 in 48 games as a keeper.

With de Villiers it is not as clear. As a batsman he averages 50 from 75 Tests; as a keeper 58 from 23. Most of the games as keeper have come since 2012, when he replaced Mark Boucher; the same time that his game started to go another level. Since then he averages 64 from 20 Tests as keeper; but in his most recent 20 Tests as a batsman, going to back to 2010, he averages 70.

The clearest exception is Andy Flower, who scored runs in industrial quantities - and went to the top of the ICC rankings - while playing as a keeper-batsman. His record as a batsman, albeit with a small sample size of eight Tests, was nowhere near as good. By contrast, Brendon McCullum's average rises from 34 to 44 when he plays as a batsman. In 2014 he made some huge hundreds, very different in nature, including 302 from 559 balls against India and 202 from 188 against Pakistan. You wouldn't know it from his frisky contributions in the last few months, when he has been understandably carried away with the sporting epiphany he is experiencing, but dropping the gloves allowed him to play the kind of innings he could not have imagined before.

The same is true of Sangakkara; only Donald Bradman has scored more double-centuries in Tests. Playing as a batsman would allow Buttler to learn how to score daddy hundreds; his current highest score in first-class cricket is 144, in Test cricket 85. In Test history, wicketkeepers have only ever scored eight double-hundreds - Sangakkara the batsman has scored two more than that.

Although he will always, like Gilchrist, transcend statistics to some extent, it would be a travesty if Buttler ended with, say, a Test average of 36 and just a few centuries and a load of jaunty 70s for us to remember. England have options if they do wish to explore changing his role. They could dry run it in limited-overs cricket, or follow the Sangakkara model of keeping in ODIs but not Tests.

It might not work. There are no guarantees, even in his current role. Australia might find a weakness outside off stump this summer and start to undermine him. But it is so rare for English cricket to discover a talent like Buttler that it is their duty to find out what he can achieve. Who knows, he might even become the world's best batsman.