I agree, the BKR rating system is one of the very neat features of this site. However, it does wildly exaggerate ratings in the first few games. There are quite a number of examples in other games where a new player has won the 1st four games (not necessarily against any strong player) and suddenly has a BKR of 2500+!
It does settle down soon after this and a 1500 BKR player might only gain approx 50-100 points from beating a 2000 BKR player. Considering that one always starts with a BKR of 1300, then that was a ~1000 points from that win!!!
Not taking anything from Nuno, but I do feel that the BKR ratings is flawed in the first few games. BrainKing simply says it is not a rated BKR and that only rated BKRs are truly reflective of ability. In other words, this anomaly is being ignored.