Complex sentence: On April 7,1986, he set a MLB record by hitting the 1st pitch of the season for a home run, eclipsing the mark held by the Chicago Cubs' Bump Wills who hit the 2nd pitch for a HR on April 4,1982.
Split into simpler sentences: On April 7,1986 he hit the 1st pitch of the season for a home run, a MLB record. This elcipsed the mark held by Chicago Cub's Bump Wills who hit the 2nd pitch for a HR on April 4,1982.