Complex sentence: By the early 1970s, he had his heart set on becoming the first black manager in the majors; the Angels traded him to the Cleveland Indians midway through the 1974 season due to his open campaigning for the manager's job.
Split into simpler sentences: By the early 1970s, he had his heart set on becoming the first black manager in the majors. In fact, the Angels traded him to the Cleveland Indians midway through the 1974 season due to his open campaigning for the manager's job.