Complex sentence: Gardner initially signed as the Royals' 1987 third-base coach, but terminally ill Royals manager Dick Howser, diagnosed with a malignant brain tumor during the summer of 1986, was forced to retire during spring training, and Gardner was promoted to fill the vacancy.
Split into simpler sentences: Gardner initially signed as the Royals' 1987 third-base coach. But terminally ill Royals manager Dick Howser, diagnosed with a malignant brain tumor during the summer of 1986, was forced to retire during spring training, and Gardner was promoted to fill the vacancy.