Complex sentence: The source of the controversy was that Bruce Gamble was competing for the Rochester Americans, because Imlach, a part owner of the Americans, was anxious to protect Rochester's roster at playoff time, as a means of protecting his investment.
Split into simpler sentences: The source of the controversy was that Bruce Gamble was competing for the Rochester Americans. Imlach was a part owner of the Americans, and was anxious to protect Rochester's roster at playoff time, as a means of protecting his investment.