A pitcher controls the tempo and “attitude” of the team and the game. If you as a pitcher show anger, frustration, even disappointment from the mound then you have just changed the tempo and attitudes of all the players on the field with you.
It is the role of the pitcher to stay stoic, unreadable and intimidating to every batter they face off with. If the players on the opposing team know they are having an impact on your emotions, they will try to capitalize on that and really try to throw you off your game.
The pitcher plays mind games with every batter they face. They work to trick, throw off, intimidate or simply outplay the batter with each pitch thrown. Even if that batter hit a home run in their last at bat against you, it’s your job to control your mind and your outlook so that player does not turn the tables and sway your confidence.
As a pitcher, I was known as poker faced and stoic. No one knew if I was happy, sad, frustrated, angry or disappointed while on the mound. The mental control that took was the hardest part of being a pitcher. You must be able to control your emotions and not allow anyone to know what you are feeling. Not just from game to game or even inning to inning but literally from pitch thrown to pitch thrown with every batter you face.
Those pitchers that can control their emotions and stay in a good place mentally are those that I have seen as not only the most successful but, they are also the ones that fully enjoy what they do and are a team leader that the rest of the players truly want to be around and play with.
So, as you learn proper mechanics, different pitches or even how to read a batter, you must also train your mind in how to handle your emotions and decide what game face you will have as you go into battle with each batter.