Complex sentence: Eric cannot catch, until one day he spontaneously reaches out and catches a stray baseball flying toward Milly's face, she tries to repeat this in school as proof of Eric's ability to catch a ball, but ends up with a black eye.
Split into simpler sentences: Eric cannot catch, until one day he spontaneously reaches out and catches a stray baseball flying toward Milly's face. She tries to repeat this in school as proof of Eric's ability to catch a ball, but ends up with a black eye.