As I ever so slowly improve at recruiting, I've run into this scenario a few times: a freshman improves nicely over non-conference play, and becomes clearly better than the guy he's playing behind - 15 to 20 points in cores sometimes. However, he's still like C- or so IQ, and the way the game is, he might walk onto the court with one shoe on, get hit with the ball, and start crying. 

The team needs what he's got, but I don't risk it until he's probably C or better for zone, at least B- for press (and I still feel icky about it).  Offense is a little less crucial, because it's the fouls and the other team's FTs than will lose the game in just a couple of minutes.

What so you, HD? Where do you feel the sweet spot is for the your favorite offense and defense?

for what its worth i started this season with 2 F zone IQs starting, and they're averaging 2.2 fouls combined

That's encouraging. In my limited experience, it seems that the impact of IQ varies between games much more than one might expect, making a scenario like this more challenging,

I suppose one approach would be to line up a non conference game around 6 or 7 where you know ahead of time that the opponent has low IQ too and see how it goes.  Anyone else?

I run Motion/Man for most of my HD life.  I would start someone at C in motion at any position other than PG, but won't let them shoot much at all until they hit a B-, and you can't be a #1 or #2 scoring option until B or B+. 

On Defense, it depends on your DEF rating.  If its good, then a C- can start, but if it is not so good I might wait until C+, and it depends on who I am playing....not starting a C+ IQ defender agains the #1 scoring option on the opposing team.

I play the triangle offense and I've had reasonable success with guys with very poor IQs.  In my first season at Rochester I had a freshman SG (Tompkins) shoot 45% from 3 while leading the team in scoring with D to C IQ over the course of the season.  In general I don't give guys without a C+ or better as much distro as I would if they had better IQs, but in the triangle low-IQ guys with low distro don't seem to touch the ball enough to become a big turnover liability...  As far as defense goes I haven't had much trouble starting low-IQ guys in the zone, but I've had better luck recruiting players with some knowledge of the defense than the offense so I haven't really tried it very much.