When Alastair Cook walked out for the toss in Chittagong on October 20, 2016, he became England's most capped Test player. At the time of writing, he holds every England Test batting record worth holding. He has made more Test runs, more Test hundreds, more Test fifties and played in more Test wins (and scored more runs in Test wins) than any other England cricketer in history.
He has captained England in 54 Tests, a record he currently shares with Mike Atherton. Since World War II, only Joe Root, Denis Compton, Ken Barrington and Len Hutton have improved on Cook's career Test average of 47.
Cook's Test average matches that of Kevin Pietersen, Ted Dexter, Peter May, Dennis Amiss and Geoff Boycott. No other England player since the war averages better than 45 runs per dismissal. Cook is also the only English player to score more than 10,000 Test runs. In the current England line-up, Root is more than 6000 runs behind.
Cook belongs in exalted company. But perhaps the most stunning thing about his career is that it has taken him fewer than 11 years to achieve all these records. That's less than half the length of Sachin Tendulkar's Test career. If Cook plays for as long as Tendulkar did, he will play nearly 300 Test matches, score nearly 24,000 Test runs and 66 Test hundreds, provided he maintains his current rate. At the end, he'll be a very tired 45-year-old man.
As Misbah-ul-Haq has shown, it's possible for an experienced player to be capable of Test-quality play after the age of 40.
For the 192 players whose careers have lasted as long as Cook's has so far, the median number of Tests played is 67. Cook has averaged one Test every 29 days during his career. Among players of comparable longevity, those who come closest to this are Mark Boucher (34 days per Test) and Rahul Dravid (35 days per Test). Tendulkar played a Test once every 44 days during his career.
Until the turn of the century, the player who most resembled Cook's unusually high frequency of Test caps was Allan Border, who averaged a Test every 36 days. Border played about ten Tests per year during his career. Cook has played 12.5. Until Cook came along, the fastest player to 133 Tests was Boucher and it took him nearly 21 extra months.
If Tendulkar had played Tests at the rate that Cook has, then he would have ended up with about 75 career Test hundreds. At first glance, these are doubtful extrapolations. In the case of elite Test batsmen (such as all those who score, say, at least 5000 Test runs), it can be safely assumed that they do not lack the quality to be regular Test players. Further, the evidence suggests that it is extremely difficult to be an elite regular Test player. We can therefore safely assume that barring injury, the risk of one of these elite players suddenly losing the ability to score runs at Test level is small.
Injuries are far more likely to interrupt their careers than selection troubles. Michael Vaughan suffered from chronic injury problems that almost certainly curtailed his Test career. Ravi Shastri played 80 Tests for India and scored Test hundreds in England, Australia, West Indies and Pakistan in the 1980s and early '90s and yet played his final Test before his 31st birthday thanks to chronic injuries.
But injuries are rare in the case of pure batsmen. Test cricket remains that rare sport in which exceptionally skilled specialist batsmen remain extremely valuable to Test teams even if they are no longer fleet-footed in the outfield.
The difficulties England have faced in trying to replace Andrew Strauss at the top of the Test batting order illustrate just how hard it is to find a quality Test batsman. Since Strauss' retirement in August 2012, Nick Compton, Michael Carberry, Alex Hales, Adam Lyth, Sam Robson and Moeen Ali have averaged 26 at the top of England's order. The search for an opening partner for Cook continues with Ben Duckett.
Root has been Cook's most successful opening partner since Strauss, but he's too important in the middle order to be considered.
Cook's position as the most prolific English Test run-getter is unlikely to be seriously challenged in the near future. Among his contemporaries, only Pietersen and Ian Bell could challenge him and neither is likely to play for England again.
Root will probably break many of Cook's records eventually, but Cook is only 31. If nothing else, Root will face stiff targets. What's more, Cook has already been through a prolonged slump, which most players who enjoy long careers invariably have to endure at least once. Root will have to endure his own slumps.
Over 134 Tests, Cook's career is marked by two outstanding series performances. He made 766 runs in Australia in a five-Test series in 2010-11, and 562 runs in a four-Test series in India in 2012-13. These two series account for just over 12% of his career Test runs and a quarter of his career Test hundreds to date in about 7% of his Tests.
Of his other five Ashes series, only one, the 2015 series in England could be considered a moderate success. Cook made 330 runs at 36 in this series. The other four series brought him 1020 runs in 20 Tests at 26.5 with a solitary century. His two South African tours have produced contrasting returns - 287 runs at 41 in 2009-10, and 184 runs at 23 in 2015-16. His home series against the visiting South Africans have been similarly contrasting. He made 329 runs at 47 in seven innings without a century in 2008. In 2012 he made 195 in six completed innings - 115 of those came in one innings.
Cook has had a happy time in India. His Test debut in Nagpur (60, 104*) was a triumph. After this it took him a further 17 innings to reach a century against India. When he did, it ended at 294, his highest Test score. That innings, like so many of his marathon masterpieces was marked by unerring judgement outside off stump and extremely disciplined treatment of length.
When India toured England in 2014, Cook had been through a couple of low-scoring years by the standards of an elite Test player. He did not make a century in that series, but it was clear that his slump was past him. Since that series, apart from a lean tour to South Africa, Cook has been his old prolific self.
For all of Cook's accomplishments, it will take a brave cricket fan to select him to an all-time post-World War II England XI today. Is he a better Test opener than Gooch, let alone Hutton or Boycott?
What is remarkable about Cook is his age. When Misbah was 31, he had played a grand total of five Test matches. He had never captained Pakistan. Steve Waugh made 20 Test hundreds after his 32nd birthday. Dravid, Tendulkar and Brian Lara made more than 5000 Test runs after they turned 32. Lara had, arguably, the best phase of the Test career after he turned 32.
Following England's triumphant tour of India in 2012-13, there was a great deal of discussion about the near inevitability of Cook breaking Tendulkar's all-time record for Test caps, Test aggregate and Test hundreds. While his subsequent slump silenced these discussions, his recent recovery ought to prompt a rethink.
If Cook plays 200 Tests, then, provided he does not suffer a slump of the kind Tendulkar suffered over his last 20 Tests, he should be mighty close to Tendulkar's all-time aggregate. Tendulkar's 51 Test hundreds will be more difficult for Cook to surpass than his aggregate. To play 200 Tests at his current rate of 12.5 per year, Cook will have to play for another six years. He will still only be 37.
With the exception of Pietersen, recent England captains - Atherton, Nasser Hussain, Vaughan, Paul Collingwood and Strauss - have retired in their mid-30s. Pietersen and Alec Stewart are the exceptions, each for very different reasons. If this pattern holds, then 200 Tests will remain a doubtful landmark for Cook. But as things stand, Cook could end his career having attained or just about crossed most of Tendulkar's all-time milestones. It will be a gargantuan achievement if he does. But even if he doesn't, Cook's place in the history books is assured.