The simple version of Sylvester Stallone's rise to fame has it that the young actor wrote "Rocky" and cast himself in the lead role, thus becoming a star overnight. Indeed, a 1978 Playboy interview began by recalling how, with that 1976 movie, Stallone had "burst upon the American movie scene like a Roman candle." As is so often the case with these things, however, Stallone hadn't simply transformed his life overnight -- he'd been struggling to break through for some time.

That very same interview with Playboy also detailed how Sly had "spent many years waiting in the wings for his career to take off," which wasn't just a metaphor. Stallone's acting career prior to "Rocky" consisted of him playing what he termed in a 1977 BBC interview to be "atmosphere." That is, after moving to New York in 1969, he spent years as an extra, playing "the guy that was being the...