I share the following story pretty frequently with pitchers I train.
When I was pitching in my first game as a high school pitcher, my well-meaning coach wanted to "help" me before the game. Right as I was leaving the dugout he grabbed my arm and angrily said, "If you walk someone you're done."
I'm seriously not kidding.
Four pitches later, I found myself sitting on the bench trying to figure out what just happened. I never had control issues before, and was never even remotely self-conscious on a baseball field before that day.
I have since learned about something called "The Law of Dominant Thought." According to noted sports psychology consultant Mack Casstevens, it can be defined as "the mind tending to remember the most dominant thought." In golf, for instance, if the mind is thinking about driving the ball into the water, the ball will likely end up there. The application for a pitcher is obvious: If he is worrying about not throwing strikes, be probably isn't.
When a pitcher is worried about not walking people, he isn't focused on throwing the next pitch for a strike to a certain location. If the coach is saying, what just might be the most ignorant and annoying thing to say to pitcher, "Just throw strikes," the pitcher runs the risk of paying attention to the coach and his words rather than focusing on the task at hand. It might sound subtle, but it is an important distinction.
Perhaps the most important step in preparing a pitcher for competition is to get him to be task-oriented. Studies show that athletes can only really focus on one thing at a time, and in a baseball game that one thing needs to be the next pitch. Any coaching on mechanics should take place at practice, not during the game._
I also believe the role of a pitching coach in a game is to make observations and share maybe one thought, if necessary, in between innings. Unless it is absolutely necessary to interrupt the pitcher during the game, comments should probably not be made from the dugout.
To wrap this all up, a prepared pitcher needs to be well rested, well fed and hydrated, have a pre-game routine to help gradually wire the body for efficient movement, and be given the chance to compete without added pressure or distractions from well-meaning coaches and parents. Staying "out of his head" seems to be a good coaching strategy.

