Baseball IQ in general, to me, is knowing the correct play. Some is instinctual, some is learned.
Which base to throw to. Knowing when you can stretch for an extra base. Understanding when a ball is hit, where you'll end up being needed for a cutoff and where the play is going to likely occur. When is it likely the other team will have a play on, and what to do about it. Reading opposing hitters' swings to position yourself a little better. Anticipating various possibilities so you're not surprised when they occur.
These things make a difference. But they're like porn....hard to codify, easier to recognize when seen.