Texan,
By low release I mean a pitcher like Seaver with his knee on or near the ground at release and a low 3/4 delivery. That could be as low as 3 ft. off the ground. Now assume a tall hitter and an umpire with a high strike zone, so 5' above the ground for the top of the strike zone. Now assume a ball going an average of 90 mph and traveling 54' to the front of the strike zone, since the pitcher releases out front of the rubber and the plate is about 17" deep. We can round that to .41 seconds travel time. Let's assume the upward acceleration imparted by the spin is 16 ft/s^2 so the net downward acceleration is 16 ft/s^2. That means the change in velocity due to gravity and spin is 16 ft/s^2 * .41s = 6.56 ft/s.
Now in order for the ball to be still rising after 54' the initial upward velocity of the ball would have to be greater than 6.56 ft/s. So let's assume that it is 6.6 ft/s such that the average upward velocity over the flight of the ball is just over 3.3 ft/s. Over 0.41s the ball will travel upwards 1.35 ft. 3' + 1.35' = 4.35' which could be the top of the strike zone with the ball still moving slightly upwards. Now one can question if the acceleration due to spin can really reach 16 ft/s^2 and if any pitcher actually releases the ball as low as 3' above the ground. On the other hand it is easy to see that an eye high pitch, the kind power pitchers get a lot of K's with could easily be still rising as it crosses the plate.