Complex sentence: He made 79 appearances for Birmingham, before suffering a series of injuries during the 2012--13 season that prevented him from playing again, leaving the club in August 2013 by mutual consent.
Split into simpler sentences: He made 79 appearances for Birmingham, before suffering a series of injuries during the 2012--13 season that prevented him from playing again. He left the club in August 2013 by mutual consent.