More than one poster in this thread has remarked that Peet shouted her lines. Was she not mic'd? Not that amplification is a complete substitute for projection, but it certainly helps a smaller performance be heard in the balcony. That way, she could have, at least, been directed to speak her lines naturally, rather than shouting and let the sound board op make sure she's heard.
If she had experience on stage, just not in venues of this size, that sort of seems like an easy fix. She should certainly have been aware of the general concept of projecting the voice, right? Once they got into the theatre for tech and it became apparent that whatever she was doing in the rehearsal studio was not being modulated enough for the larger space, someone should have been available to work with her to get her where she needed to be. I mean, it's not like getting a cat to dance a tango, right? This is an experienced actress who should have had some idea of what needed to happen, even if she needed assistance to get there.
I wonder if there were other issues, not as easily fixed or not fixable at all by that point, that manifested in shouting. Maybe it just wasn't her role, despite her seeming to be ideal casting.