a 60 mph pitch is going roughly 87 ft per second. or roughly .5 second from mound to plate. in .5 second gravity causes a ball to drop .5 * 32*(.5)^2 ( d= 1/2 g t^2 physics 101) or about 4 feet. Yeppers a pitch with no upward velocity at release will hit the ground. So EVERY pitch has some upward velocity at release. drops less, fast some, rise more. Now spin adds a new force to the equation and spin can move a pitch form its otherwise as thrown plus gravity path. The data I have seen in studies suggest ( by plotting the path of the ball for the first 20 feet than projecting where it would be with no spin that rise ball good pitchers can spin the ball up 2- 10 inches. AND MOSt are 2-6" This data was taken I believe from DI final 8 pitchers.
Now a poor batter has to starting getting on the plane of the pitch 20 feet out. All the pitch needs to do is move 2-1/4" and its a wiff. 1" and its a easy pop fly. If they guess right its a home run cause a rise in the strike zone is dead in the power wheelhouse, as another commentator noted
There was an argument about 20 years ago if you could spin a ball enough to really overcome gravity- You can't with spin alone. it was some ridiculous RPM in three digits. But with some upward RAMP and some good spin and a good drop u can make batters lives miserable. A threat of a rise makes most batters have to make decisions ( just like changing speeds does) and most batters making decisions spend a lot of time walking back to the dugout!