Complex sentence: He hit.313 and led the major league and NL with 47 HR in 1958, and hit.304 with 45 HR in 1959, and was the NL RBI leader with 129 and 143 RBI in both of those seasons.
Split into simpler sentences: He hit.313 and led the major league and NL with 47 HR in 1958. The following year, he hit.304 with 45 HR, and was the NL RBI leader with 129 and 143 RBI in both of those seasons.