This is an easy question. Music Education majors are trained in both vocal and instrumental music. While they may specialize in one or the other, I know that they have to take classes to have a basic knowlege of all instruments. You don’t have to play an instrument well to be able to be a good conductor. When you graduate, you receive a credential in Music Education, not in choral or instrumental music.

So to answer your question, sometimes the best teacher for the job is not the one who gets the job. She may be qualified, but sometimes principals make decisions based on the bottom line ($) rather than the quality of the program.

It could also be a question of senority within the district. If a position disappears, the principal must keep the teachers with the most experience.

That happened to me when I taught at a school. They had to have one of the math teachers take over part of my position as an English teacher and I was transfered to another school.