The best definition of the player with high basketball IQ comes from Van Gundy:

It’s a guy who has an innate understanding, the game comes easily to him… They see things once and it all makes sense to them. Basketball just makes sense to them and they make smart plays. They’re ahead of the play defensively. They can pick up plays you put in easily.

While doing further research on the basketball IQ on the web, I came across another article on The Crossover Movement blog. This paragraph in particular caught my eye. I believe the description extends to any player who, for whatever reason, plays out of his position. The worst, as highlighted below, is when a scorer is put into a position to be a playmaker. This rarely works well.

Combo Guards dominate the low I.Q. list: Arenas, Crawford, Ellis, Iverson, Tinsley, Jones. I have written about the difference between point guards and combo guards previously. While these players may be low I.Q. players, to me, the obvious point is that they are shooting guards trying to be point guards. As I have written before, this is a poor use of their skills and personality. They are scorers and to expect them to change and become point guards reduces their effectiveness.

It can work well, though. Dwayne Wade is a natural scorer, who excels when he has the ball in his hands. He is as good a playmaker as any point guard in the league.