I have three friends who've made careers covering roles. One did an extensive amount of road work (as he says, all the way to health insurance coverage.) They would argue mightily with the idea of a locked-in performance. Staging and individual scene blocking are of course rigidly observed. But as one friend said, to copy the existing performance would be impossible, and also throw everyone else on stage off, having to listen to one actor imitate another. Of course line readings follow the production's general textual interpretation. But within those parameters lies much room for individual stamp.
This season, I saw several covers, including Jennifer Blood on for Mare Winningham. Blood is superb, but in no way copies an actor probably 15 years her senior. Both women create a dimensional character, but Blood doesn't have the unique Winningham eccentricity, and works from a very different place, a younger, wiry, raw-boned edginess that people tell me is similar to the London performance. Both women break hearts with "Like a Rolling Stone," but both reach the devastating rawness -- that searing sense of unbidden self-examination -- in different ways. To me, seeing the show a few times, it was a master class in how actors can work within the same frame and find powerfully different takes. Both succeed..
"I'm a comedian, but in my spare time, things bother me." Garry Shandling