While Barry Bonds is the one who eventually broke Hank Aaron's career home run record, he wasn't the player of his generation who was supposed to accomplish the feat. Instead, it was Ken Griffey Jr. who was widely expected to be the next home run king, the successor to Aaron.
A valuable contributor even in his first MLB season at age 19, Griffey had an auspicious start in the majors and didn't disappoint in his first decade in the majors, eventually becoming the player the Seattle Mariners were most identified with.