For Rolling Stone, I wrote a longer essay about the secret to Marvel's success. For nearly a decade now, the studio has been on a critical and commercial hit streak, continuing with this past weekend's Guardians of the Galaxy Vol. 2. My theory: It's their directors, many of whom were oddball choices to helm major blockbusters. In the process, some of these filmmakers have ended up producing the best work of their careers. How exactly did that happen? Read on.