Somewhere I have an article that explains the "rising fastball." Being too lazy to go thru my stuff I will try and explain in easy terms.
No, a rising fastball does NOT actually rise. Gravity affects every object equally (regardless of the weight)but the spin changes pressure as explained. The eye is trained thru experience that a ball will "fall" at the rate of gravity. Example: A 90 mph fastball may fall 10 inches due to gravity and that is what the eye expects to happen. A "rising fastball," due to the pressure difference may only fall 6 inches which gives the impression that it rose. In effect, it just didn't fall as much - kind of an illusion.
Same thing for a sinker. It falls more, due to pressure than the eye expects.
Now to complicate things... which is pitching, is to throw a high hard one about 3 mph faster than your normal fastball and because the ball is in flight a shorter time, gravity does not have as much time to affect the ball and it doesn't fall as much either. It you look at the physics of hitting the ball, missing the sweet spot by 1/4 of an inch many times is the difference bewteen a flyball and a moon shot.
This high hard one is why so many kids/hitters can't lay off that pitch. It many times does not fall into the zone the same as other pitches. The secret as a pitcher is work the top of the zone with a pitch that does not come down to the location that the hitter thinks it will. That is also why high sinkers turn into moon shots, it comes down and the hitter has a great view of the front of the ball coming towards homeplate!
When Curt Schilling was in his prime with the AZ Diamondbacks, he thought pitching high/low was more important than in/out. He did pretty well with it.