I often am asked the question by my players, "how do I fool the hitter?". This question has a very simple answer that many try to over complicate. Deception in pitching has everything to do with how light your keep your arm, and for how long. The key to deception is the slingshot position. The reason it is called the "slingshot" is because when executed properly, the core pulls the arm through like that of a slingshot.
The ability to stay light until the baseball is in front of your head is the key to deception and fooling the hitter. The position that the top pitchers in the world get to is called the "slingshot" postion. The only way to achieve this position is to stay extremely light with your arm until the baseball is in front of your head.
Take a look at the baseball. See how it is coming directly from behind Maddux's head? This is what they slingshot position looks like and it is the key to deception. The baseball will come out right behind his head, giving the hitter no clues as to the velocity or type of pitch on the way.
As soon as we get heavy or feel the weight of the baseball behind our head, the hitter locks on to our arm slot. The key to throwing a deceptive pitch is to stay light as long as possible so the hitter cannot pickup his timing until after the ball is released. This is why Maddux could throw 85mph and pitch in the major leagues with success, and there are some guy who throw 95mph+ and get hit around the yard. The arm should be layed back and relaxed as the core pulls it through.
King Felix is my personal favorite example of the slingshot postion. I have followed him throughout his career and witnessed the transformation from a high 90's thrower, to a pitcher who is driving the baseball in the upper 80's, low 90's. The ball to the hitter will look like it is exploding on top of them. Even though King Felix is only throwing low 90's today, he keeps his arm so light that he is still able to be a cy young award winner year in and year out.
Advanced Readers :
The closer the baseball is to your head in the slingshot, the more deceptive the release will be. Take a look at the picture of King Felix again. Notice how tight the angle is between his head and his arm.
The slingshot is also vital for arm health and career longevity. By keeping our arm light and relaxed until we are in front of our head, we will put all the stress on our core when we turn to throw. If we are heavy behind our head, the UCL (Ulnar Collateral Ligament) is taking the majority of the stress when we turn to throw.
Take a look at Konto's arm angle and then look at Lee's. Kontos is not in the slingshot position which makes his ball very easy to pickup out of his hand. Kontos is getting what I would call "heavy" behind his head. The hitter locks on to the arm right about the same time the picture is taken. Kontos is also putting a ton of stress on his UCL. This mechanical flaw is probably the reason Kontos is a relief pitcher.
Take a look a Cliff Lee. His slingshot postion is perfect. His arm is layed back and relaxed. The baseball will come out right behind his head, deceiving the hitter. The stress from Lee's delivery will all go to his core, which is why he is able to stay healthy and pitch 200 innings a year consistently. His slingshot position is the reason he is so deceptive. It almost looks like Lee is doing a crunch, while Kontos is using only his arm to throw the baseball.
Remember, stay light as long as possible! The key to deception and arm health is the slingshot position.