I think it would just have to be explained in a couple of sentences in the Game Manual under Training, probably not too confusing. It would also help to have a reminder of this right in the Training page (i.e. listing which skills train on offense and which on defense.
Regarding Rebounding, maybe it's 2/3 defense and 1/3 offense? That's a rough estimate of how rebounds are distributed in the NBA. In BB it's actually more like 3/4 defense and 1/4 offense.
Don't ask what sort of Chunks they are, you probably don't want to know. Blowing Chunks since Season 4!