Stop everything. Drop what you are doing. Ravi Shastri may have undersold an achievement of India's Test team.

He has talked the attack up plenty, of course. In August, he announced that the team's quicks were the best India had ever had, "by a mile". But as India has for so long been the proud home of profoundly unsexy medium-pace bowling - generations of seamers diligently delivering standard-issue, ruler-straight balls at 130kph like there was a government ban on putting batsmen in discomfort - this was not exactly high praise. India's best pace attack? So what? This is like being the least annoying mosquito, or the prettiest naked mole rat.

South Africa, meanwhile, have been talking a big game about their bowling, and perhaps for good reason. During the recent Pakistan series, the captain, Faf du Plessis, said he believed he had the most potent attack on the planet. Dale Steyn then recited the averages of several of his bowling team-mates and asked: "Who's better than that?"

On the face of it, Dale, no one. But India are very close. Since the start of 2016 - a long enough time for these teams to have toured at least five of the top nine Test nations - South Africa's attack has the best average, but is closely followed by India's. Because in bowling parlance three or four average points is a substantial distance, the two attacks can be said to be well ahead of the pack.

(For the purposes of this article, matches featuring Zimbabwe, Ireland and Afghanistan have been excluded, partly because they will not be part of the top tier of the forthcoming World Test Championship).

The really interesting revelations, though, come when these figures are broken down further. South Africa's outstanding team returns, it turns out, are down largely to their attack's dominance at home. Since 2016, no side has maintained a better home average than their 22.36.

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The same must be true for India, right? I mean, this is the team that famously sets their relentless spinners loose on dustbowls. Who have their pitches "doctored", as portions of the Australian media might claim. Are they not banking on their home bowling average as well?

Not quite. Since 2016 - a period in which India have toured West Indies, Sri Lanka, South Africa, England and Australia - their away bowling average is actually slightly better than their home bowling average. They are the only team of the top nine for whom this is true.

Spinners, of course, have been a part of India's bowling success abroad. In R Ashwin and Ravindra Jadeja, they have slow bowlers who can be a force on virtually any wearing surface, in the back end of Tests. India's spinners (including part-timers) have been better in away conditions than spinners from any other nation.

But here is something truly surprising: over this period India have also had the best touring fast bowlers in the world. Which means that if you are hosting India, your batsmen are likely to face the most testing spin and pace bowling that any visiting side can produce.

As the graph above shows, South Africa are unsurprisingly not far off India's pace on the seam-bowling front. But since the arrival of Keshav Maharaj, they have a decent spin-bowling record overseas as well.

No one matches up to South Africa's quicks at home, but overseas their best bowler is left-arm spinner Keshav Maharaj (third from right) AFP/Getty Images

Where South Africa's quicks truly shine, though, is at home. In recent years, du Plessis and South Africa have been unapologetic about having their pitches emphatically suit their quicks. On top of which they have a rock-star pace attack, and arguably the best fast bowler on the planet in Kagiso Rabada.

In their own country, South Africa's quicks average a monstrous 20.25 in this period. This is way better, for instance, than the India spinners' average of 25.74 at home. According to these numbers, there is no greater batting challenge in world cricket than facing South Africa's quicks in their conditions.

(The graph above also reveals plenty about the tactics that teams other than South Africa and India employ in home series. The West Indies fast bowlers, for example, have been almost as fearsome as South Africa's during this period. New Zealand and - to a lesser extent - Australia are also heavily dependant on their quicks at home, while Sri Lanka and Bangladesh bank on spin almost to the total exclusion of seam bowling. Only India and Pakistan have maintained both spin- and seam-bowling averages under 30 at home. The excellent returns of India's fast bowlers at home further undermines the pitch-doctoring narrative.)

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Having now established that South Africa are the best attack at home, and India the best away, it is worth working out how individual bowlers contribute to these two teams' overall figures. The breakdown for home matches reveals that South Africa's main quicks are all more dominant at home than India's bowlers are at home (the retired Morne Morkel's figures are not featured here). Incredibly, Steyn is the worst of South Africa's front-line fast bowlers at home, with an average of 20.87.

Abroad, meanwhile, India's bowlers dominate the top of the table. Jasprit Bumrah - who is yet to play a Test at home - leads the way for India, with his 49 wickets coming at a stunning 21.9. The formerly maligned Ishant Sharma and the ever-menacing Mohammed Shami have excellent figures during this period as well.

There is a minor surprise on the South Africa side, which is that Maharaj has been their best bowler away from home. There is also something revealing about his presence on this list, though. He is South Africa's only established spin bowler at present. As Steyn - who is one of the greatest away bowlers of all time - has now entered the twilight of his career, and has been unable to play many away Tests due to injury in any case, South Africa could do with another competent spinner to support the developing Maharaj on tours abroad.

In contrast, look at the India names on that list - Shami, Bumrah, Ashwin and Jadeja - all outstanding bowlers, each of them posing a different threat, while workhorses such as Ishant also prosper. South Africa are ruthless at home, but few attacks in history have been as versatile as India's current bunch. And that, Mr Shastri, is at least a little more impressive than merely being India's best seam attack, even by a mile.