“Amid [its current] turmoil, the company faces an artistic challenge: The sudden dearth of experienced ballet masters who worked with Balanchine.” (Many of them had been kept away from the company by Balanchine’s successor, the just-retired Peter Martins.) “Now it’s not just the dancers who need coaches, but also a new generation of ballet masters, including Rebecca Krohn, Glenn Keenan, Craig Hall and Jonathan Stafford.” So Stafford has brought in Patricia McBride, Edward Villella, and Mimi Paul, all of whom worked closely with Mr. B. Gia Kourlas watches them at work in the studio.