No one is trying to compare Tuohy (or Starliper and Starcher) to current and former African and German pros, we are comparing them vs each other and the current high school records. It's great to have a wave of strong competitors and I hope they get to race each other.
Tuohy may appear to have a plateau in this her junior year, but the actual case is that she only ran one race all out during the indoor track season all out, which was the 3000m indoor pro race where she earned the 9:01. She won a lot of other races, including the new balance nationals DMR and 2mile, but these were not all out for best times. What she has really achieved as a junior, is that her new "average race" performance is a 9:50 2mile and a 4:40 mile, as she runs these times now regularly when she needs a strong effort. With this improved "base performance", it will be interesting to see how she does when she peaks for the big meets in June. (The XC runs in Rhode Island and at Holmdel were probably all out efforts, and the recent 4:36 DMR anchor at Penn was probably all out, as she was in come from behind mode.)
On overtraining, I really have to laugh. She's a high school junior with a very balanced life of sports, academics, social life, family and friends. One of her biggest strengths is that she fully embraces "total fitness" vs. just running, and she appears to be getting some good training advice at the local health club. Waking up and going for a run and then going to the gym does not indicate any maniacal commitment to training. The curiosity to try a long run, a local 10k road race, or a half marathon or even marathon just to see how it will go is pretty normal for a high school runner, it's naturally not part of her coaches' training plans though.
So she's not as good as the Africans, she has not peaked yet, and she is not overtrained or overraced.