Boxer Muhammad Ali used to call himself The Greatest. Maybe someday a great, exhilarating drama will be made about the once most famous, motor-mouthed, magnetic, vain, provocative, beloved and reviled man in sports history. Michael Mann’s impressionistic biopic starring the game but under-challenged Will Smith is not that drama. Mann’s film covers Ali’s life and ring career from 1964 to 1974 against a backdrop of American social and political unrest. Ali becomes involved with Malcolm X and the Nation of Islam, is married twice, has affairs, refuses induction into the army and is stripped of and reclaims his title. Mann gets most of the basics right but doesn’t quite capture Ali’s soul or spiritual growth and commitment. The film lacks depth, urgency and fleshed out relationships. It runs 2-1/2 hours but still feels underdeveloped.