As like most things, being tall has its advantages and disadvantages. In this case, however, being tall makes you naturally a better pitcher. Believe it or not, I grew up playing baseball and was the tallest kid in school. I was six foot before most kids reached four. I was most often played pitcher because I could through the ball thirty miles an hour faster than the other kids.
I don’t think it was because I practiced more than they did, I was just two feet taller than them and had a large wingspan to match. The math is pretty simple; the longer the lever the more power can be exerted. The farther away an object is from the source of power the more velocity it will take on. In this case, your core is what creates the power and your arm acts as the lever upon which the power can be distributed to the ball. The further away the ball is from your core the faster the ball will be distributed.
This is why so many world famous pitchers are always at least six-feet tall or taller. If you are short, this doesn’t mean that you can’t play baseball, it just means that you might want to play to your strengths and play another position.