Shania's not known to be a music arranger anyway. Writing is one thing, performing is one thing and arranging is another thing. Nobody does everything. Shania is a first-rate writer and performer but I don't know if she is a skilled arranger or not. She had an musical arranger for her numbers in the person of Mutt Lange. American Idol didn't invite her as a mentor because they thought she would provide nifty arrangements for the performers. She was there to give tips on interpretation and performance.