I was a Celtics fan in the late 80's, and I've never heard the nickname "The Black Hole". His Wikipedia page says his nickname is "The Torture Chamber" (which I've also never heard). The only reference I can find that mentions him being called the black hole is that teammate Danny Ainge once said he was like a black hole because when the ball was passed to him, it never came back out to the perimeter. It was easy enough to guess, but I think it was more of a pejorative and never really caught on as a nickname.
I've never heard of it either. Basketball-reference does list it as one of his nicknames, the other being Herman Munster (?), but they tend to be pretty liberal when it comes to nicknames and list some pretty obscure ones.
I also think there's too much recency bias in the quiz. Stevens and Rivers are answers but not Auerbach? Kyrie Irving but not Cousy? I would give it a little tweak.
@loganite The other members of the C's in that era had even better nicknames. No, I'm not thinking "Cornbread" or "The Hick From . . ." or "Larry Legend" or "Chief," but "Norman," which Fred Roberts got because he looked like Anthony Perkins' character in "Psycho."
I also think there's too much recency bias in the quiz. Stevens and Rivers are answers but not Auerbach? Kyrie Irving but not Cousy? I would give it a little tweak.