the conference stuff had no impact. nothing along those lines has impact. its only the ratings of the players.
my theory, which isn't proven but which i think a bunch of coaches have come to accept as i have (this was a theory i didn't accept for a long time, i probably shared this idea for the first time 8 years ago, but its only the last year or so i felt confident this is happening)... is that basically there are a handful of formulas. more or less, you can think of them as positional formulas. the formula to calculate a pg's score is not the same as a center's score. but they need to be ranked on the same big board! so i think basically HD tries to normalize the different positions to a score that can be relatively fairly ranked on the same big board.
the 40 spot jumps and drops on the board - which are not super common, but not super rare - seem to be a player changing from one position to another. i think the game basically looks at the player ratings and decides which formula to use. maybe on day 1, it thought your guy was a sg, but now he grew a bit and that tipped him over to a sf, and by the sf formula, he ranks lower (or higher).
this is somewhat controllable, i have gotten to the point where i have players higher than i expect, or lower than i expect, and i will imagine they are likely on a border. i'll adjust practice minutes accordingly. sometimes i have a guy jump 40 spots and a few games later, i get him back down by emphasizing the ratings to push him into the formula i think he had when he was ranked lower.
its far from an exact science, but my ability to predict and control the phenomenon is good enough that i am now fairly confident in the overall premise.