Complex sentence: Bill James ranked Bonds as the best player of the 1990s, adding that the decade's second-best player (Craig Biggio) had been closer in production to the decade's 10th-best player than to Bonds.
Split into simpler sentences: Bill James ranked Bonds as the best player of the 1990s. He added that the decade's second-best player, Craig Biggio, had been closer in production to the decade's 10th-best player than to Bonds.