Complex sentence: O'Sullivan missed the final black off its spot which would have levelled the score at 4-4, leaving the black ball in the jaws of the pocket, to the astonishment of everyone watching.
Split into simpler sentences: O'Sullivan missed the final black off its spot which would have levelled the score at 4-4. Instead he left the black ball in the jaws of the pocket to the astonishment of everyone watching.