Does the Practice Plan in place determine or help to modify off season rating adjustments?
Or do players just gain and lose their points according to potential, work ethic, randomness, etc.?

The latter, I’m fairly sure. I haven’t studied it though.

ETA - anecdotally here is Ivan Zerzan. Over the offseason, I had 17 points in conditioning and footwork, none in rebounding. He grew a point in rebounding, lost a point in defense, gained 3 points in ath (which was already red), while simultaneously losing points in speed and stamina.

Looks pretty highly affected by randomness.

Thanks shoe, that's kind of what I figured too. Didn't know if experts saw other results.