Note: This article was published before R Ashwin withdrew from the Rajkot Test for personal reasons.
(All stats updated till he took his 500th wicket)
In 147 years of Test cricket only eight bowlers had reached the 500-wicket landmark, but with R Ashwin there was a sense of inevitability that he would get there, long before he actually dismissed Zak Crawley for wicket number 500. The fact that he is the second-fastest to achieve the milestone - in terms of matches and deliveries - demonstrates just how successful a career he has had. You can point to his record in India (347 wickets at 21.22) and to the helpful conditions at home for spin, but nothing can take away from the expertise, consistency, hunger and the ability to improve and pick up new skills that he has shown over a career that has already spanned more than 12 years.
Since Ashwin's Test debut in November 2011 only Nathan Lyon has taken more wickets than him. Lyon's 509 is only nine more than Ashwin's current tally, but he has played 26 more matches. In fact, only two other bowlers - Stuart Broad and James Anderson - have more than 360 wickets in this period, which indicates just how colossal Ashwin has been as a Test bowler.
The first three years of Ashwin's Test career were a mixed bag: fantastic numbers at home (95 wickets in 15 Tests at 24.12) were dampened by a disappointing away record (19 wickets in eight Tests at 58.47). At the end of 2014, he already had 114 wickets from just 23 Tests, but the average was only marginally under 30.
Since then, though, Ashwin has been unstoppable. His numbers at home have improved even further (252 wickets at 20.13), while his relentless pursuit to add more variations to his bowling armoury has resulted in much better stats overseas - 134 wickets at 25.85. Even outside Asia, his average has improved to an impressive 27.41 from 23 matches; in fact, South Africa is the only country where he averages more than 33. The overseas wickets count is relatively low at 153, but that is also because he often misses out on away Tests to Ravindra Jadeja - only 40 of his 98 Tests have come away from home.
Not only is Ashwin the leading wicket-taker in Tests since 2015, his average of 22.11 is up there too. With a 150-wicket cut-off, only Jasprit Bumrah and Kagiso Rabada have done slightly better.
Hostile at home
The aspect of Ashwin's career that stands out more than any other is obviously his record at home: 347 wickets in 58 Tests at an average of 21.22. Three more wickets will make him just the fifth bowler to take 350 home wickets, after Muttiah Muralidaran, James Anderson, Stuart Broad and Anil Kumble. In terms of averages too, he is bunched together with the very best.
It's true that the pitches in India have been spin-friendly over the last few years, but even so, Ashwin has exploited the conditions better than most other bowlers. Compared to his average of 21.22, the other bowlers have averaged 33.32 in the home Tests that he has played. That's a difference of 12.09. Only two bowlers - Muralidaran and Glenn McGrath - have a higher difference in average than Ashwin. Shaun Pollock and Kumble round off the top five, with a cut-off of 200 home wickets. (The difference in average for his partner in crime in home Tests, Ravindra Jadeja, is 12.23, but he just misses the cut with 199 home wickets.)
The matchwinner
Ashwin's peak as a bowler has coincided with a phase when the Indian team has had astounding success, especially at home. India have won 42 out of 57 home Tests he has played in, and 56 of his 97 Tests overall (excluding the ongoing Rajkot Test against England). Among Indians, only Sachin Tendulkar (72), Virat Kohli (59) and Cheteshwar Pujara (58) have been involved in more wins, while current coach Rahul Dravid finished his career with 56 wins.
Ashwin's contributions to those wins have been enormous: in the 56 wins, he has taken 346 wickets at 19 apiece; only four bowlers - Shane Warne, Muralidaran, McGrath and Anderson - have more wickets in wins, and among them only Muralidaran has a better average. (Incidentally, going into the Rajkot Test, Ashwin's wickets tally in wins was exactly the same as his total wickets at home.) Ashwin's 28 five-fors in wins is next only to Muralidaran's 41. In home wins, Ashwin climbs up to third place in the wickets tally - his 275 is bettered by Muralidaran and Anderson.
There have been so many series-defining performances by Ashwin in his 12-year career that he has won a staggering 10 Man-of-the-Series awards; only Muralidaran, with 11, has done better. Eight of those are at home; the two away awards were in Sri Lanka in 2015, and in the West Indies the following year. Ashwin has played more than one Test in 29 series so far (excluding the current one), which means he has a rate of 2.9 series per award. In those 10 series, Ashwin has played 33 Tests, and taken 236 wickets at an average of 16.88. (The corresponding numbers for Muralidaran in those 11 series are: 29 Tests, 243 wickets, 15.52 average.)
A nightmare for left-handers
Of Ashwin's 500 Test wickets, 249 are of left-hand batters. No other bowler has dismissed left-handers as many times, or has such a high percentage of left-handers in his total dismissals. Anderson is next in terms of total left-hander wickets, but his 217 contributes only 31% to his total tally of 696. They are the only two bowlers to dismiss left-hand batters 200 times in Tests. In percentage terms with a 200-wicket cut-off, Graeme Swann's 47.8% (122 out of 255) is next best, followed by Zaheer Khan (42.8%), Trent Boult (42.6) and Morne Morkel (39.2).
Ashwin's average of 19.52 is the best for any bowler with at least 50 left-hander dismissals since the start of 2002. It's not surprising, therefore, that the three batters he has dismissed most often are all left-handers: Ben Stokes, David Warner and Alastair Cook. There's also a fourth, Tom Latham, in the top six. Among these four, Cook is the only one who averages more than 20 against Ashwin.
New-ball master
Ashwin has opened the bowling 50 times in Test cricket - 45 times in Asia, a couple of times each in England and Australia, and once in South Africa. In these 50 innings, he has taken 165 wickets at an average of 19.36, and a strike rate of 41 balls per wicket. The only other spinner with 100-plus wickets when opening the bowling in Test history is Sri Lanka's Rangana Herath, who has 104 wickets from 27 innings, at an average of 17.32.
These numbers, though, are in innings when the spinner opened the bowling attack; the wickets themselves may have come later in the innings. A better marker of a spinner's efficacy with the new ball is his wickets tally and average in the first few overs of an innings (though the fact that he has taken the new ball in so many innings is itself an indicator that he does that job well). Ashwin shines on that parameter as well.
In the first 10 overs of an innings, he has 47 wickets at an average of 18.89; in the first 15 overs, he has 79 at 21.26; in the first 20, the tally goes up to 121 at 20.94. In fact, Ashwin is one of only three bowlers to take 100-plus wickets in the first 20 overs of an innings since his debut in November 2011 - the other two are Broad and Anderson. Rarely has a spinner demonstrated so much expertise and skill with the new ball.
The unstoppable duo
India's dominance at home over the last decade has been built around this spin couple. In the 50 Tests that they have played together, Ashwin and Jadeja have collectively taken 511 wickets at a combined bowling average of 21.69. In those games, the other Indian bowlers have collectively taken 380 wickets at 27.63, which means Ashwin and Jadeja have accounted for more than 57% of the team's wickets in the Tests they have played together. In the 41 home Tests they've played together, their numbers improve marginally: 439 wickets at 21.32, and contributing almost 59% of India's bowler wickets. Overall, India have a 35-5 win-loss record when these two have played together, and 30-3 at home.
Only eight bowling pairs have taken more wickets in Tests together, but none of them are all-spin pairs. The next-highest among spinners is Kumble and Harbhajan Singh, who took 501 wickets at 30.23 in the 54 Tests they played together. In wins alone, the Ashwin-Jadeja pair moves up to No. 5, with 404 wickets at 18.85.
With inputs from Shiva Jayaraman and Sampath Bandarupalli