Cooper, now 67, spent 42 days with the Braves in 1980, falling one day short of the minimum.
The Boston Red Sox are calling up 31-year-old reliever Cam Booser, who has never pitched in the major leagues and was out of professional baseball for four years.
Yamamoto's reliance on his curveball and splitter through his first four outings makes his arsenal one of the most unique in MLB.