As I discuss at length in The Problem, too many pitchers' arms have been, and continue to be, ruined because too few people are asking what I think is The Question.

What do the best pitchers in the world do?

However, given the state of the game, I'd add a couple of qualifiers to The Question.

What do (and did) the best pitchers in the world (actually) do?

I add those two qualifiers for a reason...

• AND DID: The problem with studying modern pitchers is that many, if not most, move the way they do because that is what they were coached to do. Modern pitchers don't necessarily, and generally don't, move naturally. As a result, if you want to know how pitchers naturally move, you have to go back to the 80s, 70s, or even 60s.
• ACTUALLY: Despite the rapid proliferation of video, an amazing number of people, especially at the highest levels of the game of baseball, have little to no idea how the best pitchers actually moved. Part of the problem is they are still using their eyes, and the human eye simply isn't up to the task.