What really makes MLB pitchers so.. good?

As a child I never thought of being a sports player or anything - I was told it was unrealistic for anyone to try and few can do it. However about a year ago, I don't know what started it, how, or why but something made me want to make it, and something told me that I could. Opun watching them, I don't really understand that makes them so "good" and separates them from everyone else. What I've noticed that one must have

Ability to control composure

Accuracy, within a baseballs length it seems (even though I've seen people whiff at easy pitches)

Strength, to deliver the ball

Good mechanics

Deception in delivery (something I have, with an old (2011) Tim lincicum-like delivery)

A decent pitch arsenal, and with a tight rotation so the ball has a lot of break. (And ability to throw any pitch at any count)

Able to maintain a healthy body - no injuries

The drive to work hard, and not slack off

Although these things are easier said than done to achieve, I see them as very possible as for a have a great "reserve" of genetically strength. However, looking at these things I feel as if I'm missing something important that sets the numbers of how few make it. If anyone could shed light on this, I would appreciate it. Thanks