Mariah Carey struggles with ‘All I Want For Christmas Is You’ at Rockefeller Center...

Mariah Carey opened NBC’s 82nd annual tree lighting special 'Christmas in Rockefeller Center' on Wednesday. 

She performed her classic 'All I Want for Christmas Is You' live in New York City, following the song's 20 year anniversary. While it's commendable that she chose to sing live, the performance was a vocal struggle from start to finish.
 
She was flat and very pitchy. Perhaps she should consider switching up the arrangement so that it serves as a better fit for her new voice, because clearly, she cannot sing this song the way she use to.
 
Thoughts?