Like chess, pitching's a game of out thinking the other guy
Like chess, where you're thinking a couple of moves ahead, you're concentrating on the board -- you should do the same on the mound.
As a pitcher you should never tip off your pitches, show visible anger, or be predictable. Having the same mechanics for all pitches, keeping the same facial expressions, and mixing up your pitches sets you up for success.
Don't be predictible, think ahead, and check-mate your opponent. That's the key to pitching. And that's how baseball pitching is like chess.