LOS ANGELES — “Fruitvale Station” writer-director Ryan Coogler is sending a love letter to his father in the form of the latest “Rocky” film. [...] as Coogler told a story about a father-son relationship between Rocky Balboa (Sylvester Stallone, of course) and Adonis Creed (Fruitvale star Michael B. Jordan), the young filmmaker and his cast found themselves being coached off-screen by Rocky himself. Adonis never met his father, but he wants to be a professional fighter, so he goes to Philadelphia to seek Rocky’s help. When Coogler first pitched Stallone the idea of another “Rocky” film, the Hollywood veteran wasn’t too gung-ho. The young filmmaker was fresh out of graduate school, and Stallone had hung up Rocky’s gloves years earlier in 2006’s “Rocky Balboa.” The role of Adonis Creed would require an actor as dedicated to his training as Rocky was for his first big fight. Coogler directs the Oscar-nominated actor to one of the most affecting performances of his career. [...] Stallone surprised his director and co-star when he coached, er, coaxed an unexpected performance from Jordan in a particularly emotional scene. Coogler realized Jordan was suddenly crying off camera, and reshoots were needed to get the emotions on film. Coogler expected to tell a story about his relationship with his dad through Rocky and Adonis, but he got experience that dynamic with Stallone as well.