Sachs has known since about 1999 that Greece has more debt on its books than it says, because they helped hide the debt. They also, theoretically, had "insider knowledge" about the weak economies of other states as well, though that is partly conjecture based on their involvement in Greece.
But yes, this was well before all of that hit. The thing is, the BRICs are working from a rather privileged position, something I like to call "inconsistent backwardness". The paradox of backwardness states that less economically developed countries will have much quicker growing economies once they get on the right track, because they can import new technology directly, instead of having to phase out legacy systems over time. In general, that is more or less true, though there are several problematical issues with how that works out in reality. However, in the case of all these countries, they have something which gives them a massive boost over other less economically developed countries (Russia's mineral resources, espionage networks and legacy Soviet technology, for example) while retaining aspects of the paradox of backwardness which allow them to take advantage of advances from Europe and North America. They also have relatively sophisticated institutions and systems of governance. As such, they can take advantage of their relative backwardness much more effectively than, say, Liberia.