Why do tall guys shoot free throws worse than shorter guys?

Q: I am working on my 8th grade science fair project. I want to find out why do most tall NBA players have a lower free throw shooting percentage than the shorter players. I have compared the top 20 free throw shooters to 20 of the worst, and height seems to make a difference. Can you help me figure out why this statement is true?

A: My theory on that is that the tall guys think they don't have to use their legs, they're so strong, so they stop their bodies and shoot almost entirely with arm and hand. That flattens the shot and makes it less stable. Also, being so tall, I believe they don't think of shooting upward. They maybe think they can just ram it in horizontally. It's very weird.

The shorter guys can see that they need to shoot upward for the ball to come down softly, so they rely more on leg power and get higher arch.

The problem for the tall guys is that their ball flight is flat and hot and less stable. If they would just use more leg power (shoot quicker during the leg action), they'd shoot much better.

I have more to say about shooting than that, but this answers your question. That one factor, using more leg drive in the shot, will make a major difference. A tall guy who could shoot free throws very well was Rik Smits of the Indiana Pacers. He would flex his knees down and back up, catch that energy early, and get a nice high arch to his shot, and he is 7'4"! Alonzo Mourning does pretty well with it, too. Shaq O'Neal, meanwhile, has a very poor use of the legs. He used to not use them at all, and now he's trying to get some leg action in the shot but doesn't do it very well.