Sri Lanka Rowing team or Quash or Tennis teams will be similar and Cricket was also like that 50 years ago and not now!
Rugby will have more Isipathana players ! Basketball is same except Bati Zone which dominated for more than four decades!
Even swimming has some limitations though we have enough inland waterways and sea around the country!
Water Polo , Base Ball, etc are lessor known sports and we have limited coaches or no coaches.
In water Polo,quash and even Basketball we don't have sufficient trainers.
A country cannot be good in many sports and same applies to schools.
If you take Volleyball or Football or even Athletics the picture will be opposite! Susanthika, Damayanthi D, Sugath T , Manike, etc were all NOT from Colombo though Duncan White , Ediriweerasingham etc were from leading schools Kandy/colombo AT THAT TIME.
WE HAVE COME A LONG WAY IN LAST 76 YEARS AND GOOD EXAMPLE IS OUR PRESIDENT!(though not in sports)