When Sylvester Stallone first approached Tom Meehan about writing a stage musical adaptation of “Rocky,” the librettist for such classics as “Annie, “The Producers,” and “Hairspray” thought it was a terrible idea. That is, until he watched the movie with its creator and changed his mind. When Stallone then suggested R. Kelly as the person who should write the songs for the musical, Meehan reserved judgement until he met the guy. To find out Meehan’s astonished reaction to the rap star, click on the latest edition of Play By Play’s show about shows.