Founded by E. Virginia Williams in 1958, the company first appeared at Jacob’s Pillow in 1962 and returned frequently during the 1960s and 1970s. The company’s repertory has always been eclectic, including not only the classics but also works by contemporary choreographers such as Merce Cunningham, Anna Sokolow, and Talley Beatty. Since 2002, Boston Ballet has been under the direction of Mikko Nissinen, a Finnish dance artist who performed for many years with the San Francisco Ballet. Nissinen appointed Jorma Elo as Resident Choreographer in 2005, and the company presented Elo’s Plan to B at the Pillow the following year. In 2016, William Forsythe began a five-year residency with Boston Ballet, and the work excerpted here was the first new creation to result from that relationship.