Complex sentence: By 1887, he was acting at the Alcazar Theatre in San Francisco, and eventually, he was proficient enough on stage to give Shakespearean canon by the time he was twenty-one years old, though he admitted that he was the worst Macbeth ever.
Split into simpler sentences: By 1887, he was acting at the Alcazar Theatre in San Francisco. He became proficient enough on stage to give Shakespearean canon by the time he was twenty-one years old, though he admitted that he was the worst Macbeth ever.