If Delonte was a bad guy or stupid as some have suggested, I'd actually be less concerned. Stupid guys can learn over time (some do), and bad guys can grow up and improve aspects of their character. IF he has Bipolar Disorder, then we are talking about a serious mental illness that is not curable, but at best controllable. Trouble is (and this is a common dynamic among people with Bipolar), when on medication he likely feels less himself and may even feel less able to perform to the best of his basketball ability. Thus, an insidious cycle ensues: many folks go off medication and feel better (in fact feel wonderful for a while) only to result in the inevitable episodic crash. During an episode of the disorder, people will do things they'd never do when non-episodic.
I worked many years ago with a young man with Bipolar -- he'd stop his meds when he believed he didn't need them. His mania would rise and would be accompanied by deluisions (persecutorial and those of grandeur). He would believe that he could accomplish anything and he'd take on new projects and enterprises -- promising things to people that he believed he could deliver and using his supreme confidence to assure them that he would. Invariably, he crashed -- began thinking everyone was out to get him and eventually realized that he was unable to do all the things he thought he could. The result was a period of monumental depression, misery and self-deprecation -- unable to leave home; suicidal. Eventually, he'd get back on meds and return to reasonably healthy functioning. But, the awful part of the disorder is that he always knows that there is a part of him that is dynamic, flamboyant, fun and energetic -- and this part has to be kept in check or it winds out of control.
The worry for Delonte is that he may feel much more on top of his game when he's not on meds -- and if he aquiesces to his desire to stop treatment can lead to an inevitable downturn and depression. Since these episodes are not on a clear and predictable timetable, its not shocking that we didn't hear much about it during his first stint in Boston.
That said -- perhaps he doesn't have Bipolar....?