OKLAHOMA CITY — As the NBA neared its restart in late July, its players vowed to keep the calls for social justice reform at the forefront in the wake of the police killings of George Floyd and Breonna Taylor.The basketball stars weren’t the only athletes to act.In a most unusual year already thrown into chaos by the coronavirus pandemic, many athletes took unprecedented steps when a nationwide reckoning on race spilled into the streets of American cities after the death of Floyd, a Black man, during a May …