“Concussion” has the opportunity to be a provocative, stinging indictment of the National Football League, challenging the very essence of contact sports. There are moments in the film where it feels like the material is living up to its potential, inspecting the dangers of the titular brain event. The rest of “Concussion” plays it disappointingly safe, offering more defined focus on the lead character’s private life than his battle with professional football. There’s a better movie to be made about the subject, and while writer/director Peter Landesman (“Parkland”) handles a few disturbing encounters just right, the rest of the feature is much too conventional, hesitant to confront a venerable institution. Read the rest at Blu-ray.com