Comment by dannyz

While computer engines that are significantly better than the best chess players are plentiful, computer engines that are human rated and play human like moves do not exist. From the definition of ELO you could make a 1500 rated chess engine that plays perfectly half of its games and plays random moves the other half of the games, and it would stay at 1500 ELO if it continued to play against 1500 ELO players. This is an extreme example but it is not too far off from what chess engines do to reduce their ELO.