Over the last two and a half years, India have had an outstanding run of success, winning nine series in a row. Most of those, though, were in Asia. The series loss in South Africa has once again brought to the fore a familiar failing for India, and indeed for most teams: the inability to win in overseas conditions.

While India had a nine-series winning streak before this, their losing streak in overseas series is almost as long now: they have lost the last seven series they have played across Australia, England, New Zealand and South Africa. Their last such series that didn't end in defeat was in 2010-11, when they drew 1-1 in South Africa. So, while they were 21-2 in terms of win-loss between August 2015 and December 2017, they are a dismal 1-17 in their last 24 Tests in these four countries. The difference between the batting and bowling averages in these matches clearly indicates how the tables turn for India when they play in Asia, as against when they tour outside the continent.

Among India's current batsmen, only two have averaged more than 40 in these overseas Tests: Virat Kohli, who has been superb in almost all of those series except one, and Ajinkya Rahane, who has an outstanding overseas record but was dropped after a poor home season.

The difference in averages for these players tells the story. There have been six top-order batsmen who have batted at least ten times in both these sets of matches, and among them, Rahane is the only one averaging more in the overseas Tests than in the home ones, while he and Kohli are the only ones to average 40-plus in both sets of data.

Among the bowlers, the story is similar. Bhuvneshwar Kumar is the one bowler who averages less than 35 in the overseas Tests, while the others, including the rest of the pace attack, all average more than 35. The difference in averages is more than 24 for both R Ashwin and Ravindra Jadeja. In fact, Ashwin's strike rate during India's golden run (48.5) is marginally lower than his average in the overseas Tests (50.74).

While India's away numbers present a dismal picture, they are by no means the only team to struggle in unfamiliar conditions. The Asian teams have all had tough times when playing in Australia, England, New Zealand and South Africa, while the teams from those countries have all struggled in Asia. The numbers below demonstrate those struggles quite vividly, in terms of win-loss ratios and batting and bowling averages.

In the press conference after the Centurion defeat, Kohli was at pains to point out that South Africa didn't have too many winning chances in India in 2015-16, but despite that series, they still remain the best overseas team in Asian conditions during this period (and also over the few years before this), beating Sri Lanka in 2014, and drawing a series against Pakistan in the UAE in 2013.

India, on the other hand, have the poorest overseas record among the top Asian teams in the last seven years. Pakistan have lost each of their five most recent away Tests - in New Zealand and Australia - but before that, they drew 2-2 in England, and won 1-0 in New Zealand in 2011. Sri Lanka's win-loss of 2-15 is marginally better than India's during this period. They have lost nine of their last ten Tests in these countries, but before that, they did win a Test series in England 1-0 in 2014.

These stats also highlight why there is so much talk about India being poor travellers. While most teams have struggled abroad, India have struggled more than the rest, with the poorest win-loss ratio, and among the worst difference between batting and bowling averages. Those numbers look even more incongruous given they belong to the top-ranked team in the world.

That wasn't the case between 2002 and 2010, a period during which India were extremely competitive overseas: in eight series, they won two, lost three, and drew three, and had a 7-9 win-loss record in 25 Tests. In that period, India averaged 35.66 with the bat and 38.02 with the ball, a difference of only -2.36. Compared to those highs, India's overseas numbers have declined steeply in the last seven years.

Before the team embarked on the tour to South Africa, the captain and coach gave all the right sound bytes about how important it was for them to win overseas. For a player as driven as Kohli, it is clearly important that his team is recognised as a winner in all conditions; in that light, his complaint about the cramped scheduling of the South Africa series was justified. However, in the end, a team can only be judged by results, and this Indian team needs more wins outside Asia. Luckily for them, over the next 15 months there will be several more opportunities to do what they haven't been able to so far in South Africa.

S Rajesh is stats editor of ESPNcricinfo. @rajeshstats.