Who directed a 2015 American sports drama film that was a spin-off and sequel to the "Rocky" film series, the film features a British professional boxer who held the WBC cruiserweight title from 2016 to 2017? 
Tony Bellew:  He held the WBC cruiserweight title from 2016 to 2017, and previously the British and Commonwealth light-heavyweight titles between 2010 and 2014, and the European cruiserweight title from 2015 to 2016.
i don't know