The limitations that this leads to become obvious when one looks at MEA’s territorial divisions. The MEA has a single joint secretary to look at North Korea, South Korea, China, Japan, Mongolia, Taiwan and Tibetan refugees. A single joint secretary handles all the 20 Latin American countries and a dozen Caribbean countries in New Delhi and India does not post full fledged ambassadors to smaller but important Latin American countries like Bolivia, Paraguay and Uruguay. The entire South East Asian region, comprising the 10 ASEAN member states, along with Australia and New Zealand is handled by one joint secretary.
http://www.stratpost.com/indian-diplomacy-fails-numbers-test
Indian diplomatic corps is about the same size as Singapore.