Complex sentence: Marrone started in the opening match of the 2012--13 season against Parma in a 2--0 win, replacing the injured Giorgio Chiellini in an unfamiliar position as centre back but managed to help keep a clean sheet.
Split into simpler sentences: Marrone started in the opening match of the 2012--13 season against Parma in a 2--0 win. He replaced the injured Giorgio Chiellini in an unfamiliar position as centre back but managed to help keep a clean sheet.