The overseas factor in the IPL

One of the key aspects of the IPL is the concept of putting together top-class international players from different countries with domestic cricketers, some of whom have hardly played much first-class cricket. For the foreign players, the challenge is to live up to their top billing, and justify the amounts invested in them, as also to get used to conditions that some of them may not be familiar with. Players from some countries have been a bigger success than others, and have greatly impacted the fortunes of their sides. Here's a look at the country-wise batting and bowling numbers in the IPL, and the amount that each franchise has relied on its overseas stars.

It's obvious that overseas players are expected to contribute significantly, since many of them are among the best in the business. Not surprisingly, the overseas stars have put in plenty of game-changing performances: in ESPNcricinfo's analysis of best displays (updated till May 6), 31 of the top 50 batting performances, and 27 of the top 50 bowling ones, are by overseas players. The top run-getter is a foreign player (though there are plenty of Indian names among the top few as well), while the three best bowlers in the tournament are all overseas ones - Lasith Malinga, Morne Morkel and Sunil Narine.

Among the various foreign players, the Australians and the South Africans are the ones who've had the most impact on the IPL so far, with both bat and ball. Australia didn't have a full presence in the early part of the IPL since some of their players were away on tour to the West Indies, but despite that they've scored the highest number of runs among foreign players, and taken the second-highest number of wickets. Several of them have made strong cases to be included in the World Twenty20 in Sri Lanka later this year.

The most consistent from Australia in this IPL has been Cameron White. He hasn't always enjoyed the IPL, but this season he has been the one bright spot in a sea of misery for Deccan Chargers, with 410 runs - the sixth highest - at 45.55 and a strike rate of almost 152. Steven Smith, Shaun Marsh, David Hussey and Brad Hodge have done pretty well too, and with Shane Watson and David Warner showing terrific form, the Australian contribution could be even more in the last couple of weeks of the tournament.

The two other national sides that have contributed 1000-plus runs are South Africa and West Indies, thanks largely to the outstanding form of Faf du Plessis, AB de Villiers and Chris Gayle. New Zealand, on the other hand, have been largely disappointing, with both Ross Taylor and Brendon McCullum struggling for runs.

All stats updated till May 9

Among the bowlers, though, South Africa have been the biggest overseas contributor, with 71 wickets, of which 41 have been taken by Morne Morkel, Dale Steyn and Jacques Kallis. Sri Lanka's numbers are outstanding because of Lasith Malinga and Muttiah Muralitharan, while Sunil Narine's mystery spin has propped up the numbers for West Indies.

The Indians have contributed 52% of the total wickets taken by bowlers in the tournament, which is slightly lower than their percentage contribution of runs.

All stats updated till May 9

Gayle and de Villiers have been outstanding with the bat for Royal Challengers, while Tillakaratne Dilshan has played a fine supporting role, but the Indian batsmen have contributed little to the team, apart from Virat Kohli's innings against Mumbai Indians. That's clear from the table below too, which shows the runs scored by Indian and overseas players for each team. The Indian players have scored only 637 runs for Royal Challengers at an average of 16.76 and a striker rate of 111, while the foreign players have scored more than 1000 runs, averaging almost 41 at a strike rate of 145. In fact, they're the only team for which the overseas contribution has topped 1000 runs.

On the other hand, for Mumbai Indians and Kolkata Knight Riders, the home batsmen have scored more runs at a better rate than the overseas ones. Mumbai Indians haven't had one outstanding batsman, but most of their runs have come from Rohit Sharma, Ambati Rayudu and Sachin Tendulkar, while Gautam Gambhir has been by far the key man for Knight Riders.

The overall bowling averages are much better for the overseas bowlers - they average 22.41 per wicket, compared to 33.36 for the Indian bowlers - and for four teams they have taken more wickets than the Indian bowlers. The difference is most stark in the case of Knight Riders - the overseas bowlers, led by Sunil Narine, have taken 42 wickets at 19.28, compared to 19 wickets by the Indian bowlers. In the case of Royal Challengers, their Indian bowlers have taken 32 wickets, but at a poor average of 40.41 and an economy rate of almost nine; the overseas bowlers have conceded only 26.85 runs per wicket, and have a much better economy rate too. Similarly, Malinga and Morne Morkel have significantly improved the averages for Mumbai Indians and Daredevils.