Complex sentence: Although still able to win his club's best and fairest award in 2000, he was not the imposing player of the past; who at his peak was rated by many as one of the very best players in the competition.
Split into simpler sentences: Although still able to win his club's best and fairest award in 2000, he was not the imposing player of the past. At his peak he was rated by many as one of the very best players in the competition.