Complex sentence: Then Johnson finally made it into the major leagues for a stretch beginning in with the Los Angeles Dodgers, when a broken ankle in early May sidelined Tommy Davis, their regular left fielder, for the remainder of the season.
Split into simpler sentences: Then Johnson finally made it into the major leagues for a stretch beginning in with the Dodgers. A broken ankle in early May sidelined Tommy Davis, their regular left fielder, for the remainder of the season.