Complex sentence: Eppy played with St. Louis Kutis S.C. during the mid- 1950s when they were a dominant U.S. team, winning the 1957 Amateur Cup and U.S. Open Cup.
Split into simpler sentences: Eppy played with St. Louis Kutis S.C. during the mid- 1950s when they were a dominant U.S. team. Kutis won the 1957 Amateur Cup and U.S. Open Cup.