If you think you need to be a voice teacher or a professional to know the intricacies of vocal technique, then you need to reassess. All you need, honey, is training (minimal at that), which I have, to know that Naya was doing more yelling than singing. This happens when people have to reach for notes. It's not rocket science.

Also, generally it's considered bad singing to not be able to hit the notes. Professional singers are advised not to, so yes, Naya should not. On the other hand, I don't really like Amber's voice, but she always hits her notes. Naya doesn't have Amber's strength or range and it showed.