From the interview:
McWhorter: “For the first time in the ballet’s history, we’re performing live music to Swan Lake. This is a piece that Toni Pimble choreographed a long time ago. But they’ve always had to do it with recorded music. To a lot of people, I think, you say you’re playing Tchaikovsky’s Swan Lake, that basically means there’s a score, there’s all these parts, and it just kind of comes in this neat little box and you just kind of perform it. Not so in ballet, if we were doing a symphony, no question, that’s likely what would happen. Ballet is really much more of a fluid dynamic. What we are accustomed to with Tchaikovsky’s Swan Lake, it’s not exactly what Tchaikovsky wrote. It went through massive changes after he died with the conductor that was at the imperial ballet in Russia, that changed how all of these things kind of fit together. Fast forward 100 years, to one of Toni Pimble’s teachers who used a version of it. And even Toni has done some changes. So actually there are 80 changes from the original score to what we do now. And that took all summer for Sarah Viens and myself to kind of put together a score and all the parts.”
https://www.klcc.org/post/eugene-ballet-orchestra-next-perform-swan-lake