William Forsythe’s new company looks a lot like his old Ballett Frankfurt. “At first, watching Forsythe’s 18 dancers, it is not particularly evident what has changed. They are still based, like the old company, in the studios of Frankfurt’s Opernhaus, and as they wait to begin work, swigging water and easing soreness out of their muscles, they look like any bunch of dancers, anywhere in the world. Slowly, however, it becomes evident that this new ensemble possesses a very singular dynamic.”