Anyway, the thing that struck me about her performance was her lack of control over her voice (the transition from her lower to upper registers, and some of her vocal affectations seemed a little 'off' to me, though I'd have to rewatch to give a better analysis). Basically, she sounded like someone who hadn't been practicing with any regularity. I agree with you though, that she's not without talent. She just needs to practice more and perform more, maybe have a voice teacher help her out with those affectations that sound good (to me) on the recorded versions.
That said, whether or not it was a good idea to put someone live on national television when they're not at the top of their game (and she definitely isn't) is another matter entirely... I have to wonder who thought that was a good idea.