Her singing isn't the problem. She's a perfectly capable and credible singer, delivering capable, credible vocals.
The problem is that she doesn't know how to act on stage.
This isn't even a case of giving a performance for the cameras; see Mary-Louise Parker in HEDDA GABLER. A strange as Parker was, there was a distinct character there.
There's no distinct character in Graham's performance. She's a dead fish.
Slight threadjack, but these are clips of Lorna Luft as Adelaide in the national tour that followed the 90s revival. She almost got the part on Broadway, but (story of her life) Faith Prince beat her out.