Maybe lay it out in terms they understand; “in order to be considered as PROFICIENT(OER)/EXCEEDS THE STANDARD(NCOER), you may be required to perform up to X hours of unit work between drills. In order to be considered for EXCELS(OER)/FAR EXCEEDS(NCOER), you may be required to perform up to Z hours or unit work between drills.” Is that an option in addition to the retirement/pay options?

I agree with @brownhd and think that the evaluations are more focused on the outcomes rather than how the the leader got to those outcomes.  If they did a great job with minimal effort, that’s just as great as if they did a great job and put in 100 hours during planning.  I do think that, in general, you can tell who put in the extra effort and time and that is something you could certainly discuss during initial counseling.

I was recently talking to a class of reserve Captains and joked that the Army gets one hell of a value out of TPU/M-Day Commanders.