Complex sentence: At the U.S. Championships, competing for the second time on the junior level, Mroz placed 3rd in the short program and 2nd in the free skate to win the silver medal overall, placing 10.13 points behind champion Rippon.
Split into simpler sentences: At the U.S. Championships, Mroz competed for the second time on the junior level. He placed 3rd in the short program and 2nd in the free skate to win the silver medal overall, 10.13 points behind champion Rippon.