"The best pitchers have the best imagination."

I was told this by a mentor of mine years ago, and I feel like - although the game has changed into more of a" power first, control second" world -there is a mental edge pitchers must attain to finalize their greatness.

20, or even as recently as 10 years ago the ability to change speeds and hit corners was a prerequisite for most every elite pitcher.  This is not the case in modern times.  Most pitchers (and parents) are seeking to maximize velocity from Little League age.  Aside from the obvious and often talked about injury risk from throwing too hard, too often, too young, the focus on recognizing when to change speeds or learning how to keep the ball a little inside or outside occasionally is no longer a priority of a pitcher's development process.