Complex sentence: Born in Barcelona, Catalonia, Sánchez Broto joined the Real Zaragoza academy at 14, where his failure to make an impression as a forward led to his being used as a goalkeeper.
Split into simpler sentences: Born in Barcelona, Catalonia, Sánchez Broto joined the Real Zaragoza academy at 14. His failure to make an impression as an attacker led to his being used as a goalkeeper.