Complex sentence: In January 1996, Kramnik became the world number-one rated player; although having the same FIDE rating as Kasparov (2775), Kramnik became number one by having played more games during the rating period in question.
Split into simpler sentences: In January 1996, Kramnik became the world number-one rated player. He had the same FIDE rating as Kasparov (2775), but became number one by having played more games during the rating period in question.