Now I've gone and done it. I'm sorry, already yet.
College coaches call college games and they want pitchers to work away-away-away and come inside only to surprise them, because a mistake goes 400 feet with metal. Not many college pitchers will come inside behind on the count because the margin for error is so small.
In the NY-P, catchers learn to call ballgames and pitchers learn to work inside consistantly so they can get hitters out inside and outside. If they can't work inside consistantly, hitters can sit on pitches out over the plate and hit them hard and/or a long way. Hitters can't do that if they're conscious of getting sawed off.
Another way to look at it: College coaches know they can get a decent number of hitters out of pitches out of the strike zone. Pros have to get hitters out on balls and strikes.