An evaluation builds upon the elements of description and context noted earlier. Also, the critic must evaluate separately the performance of the particular dancers on stage on a particular day and the choreographic design, which exists independently of that performance. Performance is more easily evaluated. Judging choreography is more difficult, but a good foundation laid in the description and contextual analysis helps. For an established masterwork, a critic today needs to make no new judgment, although it serves new audiences to explain why a certain work is considered a masterpiece.
Much new choreography fits into an existing genre.
For example, a work may use an idiom developed by George Balanchine or Paul Taylor. There is nothing wrong with this. Choreographic geniuses do not emerge regularly and routinely and it is not easy to master an important idiom by an established choreographer and use it for creation of a new work. Even after masterworks and works in the style of an established master, a few new, genuinely novel, works will remain. It takes several viewings of real breakthroughs to develop a good sense of whether they are mere gimmickry or the emergence of important new genres.