For clarity’s sake, there should be a limit to the length and grammatical complexity of appositives. An appositive or appositive phrase, after all, is supposed to be only a simple and quick qualifier of a subject before the verb, as in “The woman, a radiant transformation of the skinny teenager that she used to be, charmed everyone during her debut.” Extremely long and structurally convoluted appositive phrases—endemic in sports news writing, as in the case of that sentence you presented—only serve to obstruct narrative flow and confuse the reader. This also often happens when gung-ho press agents forcibly pack into their lead sentences so many disparate details about the subject of their press release for fear that news editors might cut off those details if they are presented later in the press release. Of course, news editors are supposed to routinely temper such longwinded bursts of appositive enthusiasm, but they (news editors) are sometimes too accommodating or too busy or too lazy to boil them down into simpler, more readable grammatical forms for the reader.
So what should be the limit to the length of appositives? Nothing that we can cast in stone, of course, but appositives shouldn’t be too long and too structurally complicated as to unduly tax the patience and powers of comprehension of the reader. I would think that the lead sentence you presented has breached that limit.
Here’s how a more circumspect news editor with an eye for clarity might have pared down that extremely convoluted sentence:
“Joe Frazier, the all-time heavyweight boxing great who beat the then undefeated Muhammad Ali, died on Monday, his family said in a statement.
“Frazier, the son of a South Carolina sharecropper, punched meat in a Philadelphia slaughterhouse before Rocky and later won the boxing gold medal in the Olympics…”
In sports news writing, though, I must acknowledge that extremely long and complicated appositive phrases tend to be the rule rather than the exception. The rapid-fire, staccato language of sports reporting just seems to reflect the breathless excitement that’s elicited by a well-fought sports event.
