Complex sentence: Agee, still a prospect in 1965, would win the American League's Rookie of the Year award in, and would be traded to the New York Mets, where his hitting and fielding would be a major factor in their World Championship season.
Split into simpler sentences: Agee, still a prospect when traded, would win the American League's Rookie of the Year award in. He then would be traded to the New York Mets, where his hitting and fielding would be a major factor in their World Championship season.