Mu is a middle distance athlete. Is she really the only non-sprint athlete in that group? The British 800m runners spend a proportion of the year training at altitude. Or at very least they go to Potschefstroom which is nearly at altitude.
Mu's demise is an absolutely catastrophic failure of coaching and lack of preparation by the coach. She obviously has a problem with tactics and placing herself in races so as not to run into trouble, but there appears to have been no effort in the last 3 years to work on this. Instead, she has raced less and less and is out of practice. She was already an inexperienced tactitician, despite being an Olympic gold medallist, because she's so young. What sensible coach fails to work on tactics and developing the athlete's racing brain?
Perhaps the athlete is very difficult to train, but she doesn't seem all that difficult, just anxious, slightly troubled and not very happy. The athlete herself needs to have a think about what might work better for her, if she wants to be successful. Didn't she go to Kersee's group in the first place because she was following her boyfriend and then broke up with him and found it hard to train? What sort of advice is she receiving with regards to her personal life and how not to throw away her career like this?