P.V Narasimha Rao was the architect of economic reforms in India and Manmohan Singh is thanklessly hijacking all the credits due to PVN. If M Singh is so much capable and diplomatic, he should be able to continue with the same reform process now. But, If you look back to last three years of economic scenarios in India, reform process is in stagnant mode. He cannot even handle the black mailing from Left parties. Manmohan is so thankless that he never ever acknowledged his political mentor PVN and became a tool in the hands of Sonia Gandhi. What ever deficiencies PVN had, he was one of the best PMs of modern India and the level of his diplomacy was evident in the involvement of oppositions in key decision making process. Manmohan Singh is an utterly failed PM in every sense. Congress and he were trying to use Nuclear for their on political mileage without even taking any political parties in to confidence.
So M Sigh is a failed PM in all sense, whether it be diplomacy, political reform, economic reform, handling terrorism etc. etc.