West Side Story was a risk because musicals did not often have such downbeat endings. It was hardly a sleeper although it was not the super smash we think it was. It took the film version to make it an American classic.
However, a sleeper is not just about the actors, but about the creators as well. West Side Story had two powerhouses, Jerry Robbins and Leonard Bernstein plus Artie Laurents was not exactly chopped liver (as he will be the first to tell you).
A sleeper has very little in the credits that stir interest. 1776 had a name choreographer (Onna White) for a show that was not heavy on dance and that's about it except for the designers. The source material was highly suspect as well--the Declaration of Independence? Come on.
Wedding Singer cuts no new ground as a film anywhere. You knew where it was going to end at the beginning. My concern is will this hurt the show? Having no expectations could cut into an advance sale.
If the reviews aren't there in spades, then its a goner.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher