Hey Lew:
Eligibility of Performers.
i) In order to be eligible, an actor or actress must perform in the role on the production?s opening night and must perform in the minimum number of
performances to which the producer of such production must invite and make tickets available to Tony voters as required by Rule 2(a)vi).
ii) If an actor or actress is otherwise eligible but is repeating a role for which such actor or actress has won a Tony Award previously, such actor or actress shall not be eligible regardless of the category that role may have been placed in previously.
Also, Jennifer Hudson was eligible for a nomination because THE COLOR PURPLE was revived, and thus it was a "brand new" show, so to speak.