The story of Dr. Bennet Omalu — the Nigerian coroner living in Pittsburgh who identified a pattern of brain damage among veteran American football players and was persecuted for it rather than praised — is fascinating. It involves conspiracy, whistle-blowing, hard science and a doozy of a question: what do you do when the national pastime proves dangerous to health? The movie Concussion, which tells this story, is a middle-of-the-road drama populated by stock characters. At its heart is a single impressive performance from Will Smith as Omalu, notable because, with his thick, mellifluous accent and gentle, precise mannerisms, this is the least Will Smith turn we’ve seen yet. But writer/director Peter Landesman has turned out a film that nonetheless remains desperately conventional and never communicates that sense of inspiration.