French horn college auditions chances ?

My son recently auditioned to his music schools for French horn performance. His top choices are Carnegie Mellon and Northwestern. I’m pretty scared for him because in most of his auditions he didn’t play how he normally does. What do you think his chances are? As far for academics he has a solid 4.6 weighted GPA and ok SAT score. He also attended interlochen last year on a full scholarship and will be attending BUTI tanglewood’s YAO program this year on a scholarship.