R Ashwin is in the form of his life. In the last six months he has taken 57 wickets in eight Tests, at an average of 14.38, with seven five-fors. During this period, he has taken 41% of all wickets by Indian bowlers (57 out of 138), and 70% of all five-fors (seven out of ten). He has won one Man-of-the-Match and two Man-of-the-Series awards. Things couldn't be any better for him.

Ashwin's success comes after a period of struggle, when he lacked penetration and looked toothless: in his previous six Tests, between December 2013 and January 2015, he managed only 15 wickets at 52.86, and bowled, on average, 100 deliveries per wicket. It is true that all of those six Tests were outside Asia, and all of his recent successes have been in the subcontinent, but it would be unfair to attribute all his results to only the favourable conditions: he was superb during the 2015 World Cup too in Australia and New Zealand - taking 13 wickets at 25.38 - and has since been on a roll, running circles around opposition batsmen.

His numbers in Asia are truly mind-boggling: in 23 Tests in the continent he has taken a staggering 152 wickets - that's an average of 6.6 per Test - at an average of 20.47. His wickets tally is easily the best for any bowler after his first 23 Tests in the continent. The next-best, in terms of wickets in Asia after 23 Tests, is 130, by Waqar Younis; Harbhajan Singh had 114 after his first 23 Tests in Asia, while Anil Kumble had 112. Ashwin's stats outside Asia are less flattering, but the sample size there is small too - only nine Tests: six in Australia, two in England and one in South Africa.

Among all bowlers who have taken at least 100 wickets in Asia - there are 25 bowlers in this list - only Imran Khan has a better average than Ashwin's 20.47. Waqar comes in next at 20.64, followed by Muttiah Muralitharan (21.69) and Wasim Akram (22.53). Clearly, Ashwin is special in Asian conditions.

His average in Asia is outstanding, but how good is his average relative to the overall bowling average in these matches? Has he benefited from pitches being very bowler-friendly, and overall scores being very low in these matches? The last two columns of the table below offer some answers. In the 23 Tests that Ashwin has played in Asia, the overall bowling average is 30.32, which means his average of 20.47 is 1.48 times better than the overall average. Only two other bowlers have a better ratio (among those with 100 Test wickets in Asia) - Imran and Murali - while Shoaib Akhtar's average was 1.48 times better as well.

Kumble averaged 27 in Asia, but the matches he played here were generally more high-scoring - they produced an average of 35.64 runs per wicket - which means he was 1.32 times better than the overall average. Javagal Srinath had a marginally better average, but his ratio is poorer as he played in Tests in which fewer runs were scored. Kapil and Pragyan Ojha have poorer averages but ratios that are as good as Srinath's, as they played in games that produced more runs.

* Overall bowling average in the Tests that he played in Asia
The strike force
In 2015, Ashwin has taken a wicket every 36.4 balls, which is fourth-best among the 783 instances when a bowler has bowled at least 250 overs in any calendar year, and the best among spinners. The only bowlers with better strike rates in a calendar year are Waqar (29.5 in 1993), Dale Steyn (35.8 in 2008) and Sydney Barnes (36.0 in 1912). Among the top ten in this list, Ashwin is the only spinner; the next-best among spinners is Murali's 39.2 in 2006, while the next-best among all Indian bowlers is Zaheer Khan's 39.8 in 2010. (Click here for the full list.)

Scourge of left-handers
In his last two series - against Sri Lanka and South Africa - Ashwin has dismissed 32 left-handers at an average of 9.96 per wicket; against right-handers, he has averaged 20.30 (20 wickets). His exceptional control, his ability to deceive batsmen with flight and guile, and his ability to turn the offspinner makes him a handful for right-handers as well, but it's clear that left-handers find him an even bigger force. In these last two Test series, he dismissed Stiaan van Zyl five times while conceding 13 runs (average 2.60), Dean Elgar four times (average 13.75), Kumar Sangakkara four times (5.75) and Lahiru Thirimanne four times (12.75). Admittedly, not all those names are exceptional players of spin, but these numbers indicate the stranglehold he has against left-handers.

In the period since Ashwin made his Test debut, no bowler has dismissed left-handers as many times as Ashwin has. In fact, no bowler has even come close. Ashwin has 100 left-handers' wickets, at an average of 18.44, which is also the best among bowlers who have taken at least ten left-hander wickets during this period. The next-best in terms of wickets in Trent Boult with 62, while Mitchell Johnson's average of 20.30 is the closest to Ashwin's 18.44.

New-ball specialist
With India often playing home Tests on turning tracks, there have been situations requiring a spinner to take the new ball: Ashwin has answered that call every time. He has opened the bowling 19 times - 13 of them at home - and has taken 70 wickets in those innings at an average of 17.37. Only three spinners have taken more wickets in innings when they have opened the bowling - Hugh Trimble, Bobby Peel and Colin Blythe - and they all played more than 100 years ago. Ashwin has nine five-fors in these 19 innings, which is the highest for spinners in innings when they have opened the bowling.

These overall stats, though, don't necessarily mean a spinner took wickets with the new ball; the wickets tally includes the entire innings when the spinner opened the bowling, which means he could have bowled a couple of overs with the new ball, and then returned later to take his wickets with an older ball. With Ashwin, though, that isn't the case: in the first 20 overs of an innings he has taken 41 wickets, at 17.95. Since the beginning of 2002, that's the most wickets by any spinner in the first 20 overs of an innings in Tests, two more than Murali, and five more than Rangana Herath and Graeme Swann. In the first ten overs of an innings, he has 20 wickets at 15.40, again the best among spinners - Herath is next with 15 wickets, at 22.26.

The series winner
In just 11 Test series that he has played (excluding one-off Tests), Ashwin has won five Man-of-the-Series awards, which is the most by any Indian player. Sachin Tendulkar and Virender Sehwag won five such awards too, but over much longer careers. In the history of Test cricket, only ten players have won more Man-of-the-Series awards.

With so much going his way in 2015, you'd expect Ashwin to continue that form in 2016 as well. If he is among the wickets in Tests next year, it will be the first time Ashwin would have had two successive great years in Tests. So far, he has been outstanding in the odd-numbered years, but quite ordinary in the even-numbered ones. That's in large parts due to the schedule, though Ashwin did have a poor home series against England in 2012, averaging 52.64 in four Tests.

In 2016, though, India have a Test in Zimbabwe and four in the West Indies lined up, before hosting New Zealand (three Tests), England (five Tests) and Australia (four Tests) over a busy 2016-17 home season. That looks like an itinerary which will give Ashwin every chance to put an end to his even-year jinx.