Were they on anti-depressants? Did the hypnosis commands to "help them focus" create a "focus compulsion" that they couldn't control because of their meds? Did this hypnotic focus compulsion, driven by the meds, force them to focus on distracting or destructive thoughts, that they then couldn't pull out of? Did the principal suggest that, now that they had hynotic help, they could cut back on their meds (a known trigger of depression) and thus induce the very depression they then couldn't tear their minds away from?
One of the links above show that this guy was selling a book(?), or a video (?) through Amazon purposting to help young baseball players “focus”. This is really creepy.