I actually agree with you about Yu-na being at the Cricket Club, and if everything went down the way Brian says it did, she should have left earlier.
For the record maybe leaving Brian won't be so bad for Yu-na. Maybe another coach could help her improve that triple loop, which she may need with Mao getting her act together. Orser's a brilliant technical coach but I'm not sure teaching the loop is one of his strong points. Considering it was his problem jump, and well Christina isn't a strong loop jumper either. While the jump was always a problem jump for her, she actually landed that jump quite a bit as a Junior, never at Junior worlds but at other competitions. So maybe with someone who doesn't have his own issues with it, she might be able to improve it or get confidence with it.
Every coach has their strengths and weaknesses, and sometimes leaving a coach even a great one, can help you improve on your other areas.