#4 Dwight Howard - 13 inches
Before Howard's huge growth spurt, he was a point guard, was a good shooter, had been serious about basketball since the age of 9, and stood at 5'10" when he was in 8th grade. He was not seen as an NBA prospect but the next two years of his high school career changed his entire life.
According to Nick Halili of the Dub Magazine, Dwight grew almost a foot and stood at 6'9"! That was a freak of a growth spurt! Despite having a tall frame, Dwight was quick and versatile enough to play as a Point Guard, but later on, he had to change his game as per his height.
Then he grew a couple of inches more and now he is 6'11" tall. He was drafted in the NBA as was considered as the so-called second coming of Shaq before he got drafted to the league.