3. Keldon Johnson (Age: 22)
It might seem unfair to Keldon Johnson to have him third on this list, but hear me out. He's already had a meteoric rise from year one to two. Going from showing up in 17 games to being a full-time starter from day one in your second year is no easy feat under Gregg Popovich.
Johnson did well in his role, establishing himself as a wrecking ball down low frequently in the mix for loose rebounds and putbacks. He also became a fantastic finisher and used his driving ability to great success last season.
After gaining more exposure with his improved play and then his time with Team USA this summer, opponents seem to have a solid strategy defending Johnson. By backing off him in the halfcourt, they're effectively taking away his biggest strength while leaving him open for his biggest weakness -- his jumper.
An outside jump shot would do wonders for Keldon's game since his drive is already so lethal. In fact, if the preseason is any indication, his driving game may have gotten even better.
Just because he's already had a quick rise in the NBA doesn't mean he can't have another one. To reach new heights, he'll need to develop a reliable mid-court move like a floater or jumper from the free throw area. A 3-point shot would be even better.
Johnson has a lot of natural talent and the body to be really special in the league. He just needs to put it all together.