Aroldis Chapman, does a whole lot right. I mean you have to if you want to throw 105 mph. So why then was Chapman on the DL for the majority of the 2011 season with shoulder inflammation? In one word, DECELERATION.
In Chapman’s case, he’s throwing the ball 105 mph. The split second after release, the arm travels much faster as it is freed of the 5 ounces of baseball. I had this measure on myself and it was approximately 8 mph faster than pitch speed. So assuming the same for Chapman, he has to stop an arm going approximately 113 mph. And he has to do it without damaging his arm. That’s a tall order, but it has been done.
Randy Johnson through high 90’s and even 100’s while holding a long career in baseball. Similarly, Nolan Ryan was a flame thrower and nobody threw for more years in the Majors. Obviously, they didn’t throw 105 mph, but band deceleration has hurt arms moving a lot slower.
The main deceleration problems can be separated into pronation and arm bend.
Pronation of the arm, the second after release puts the stress of deceleration on the large deltoid mucle instead of the delicate ligaments and tendons of the rotator cuff. It also spreads the stress over the large back and lat muscles. Check out the difference between Chapman and Johnson/Ryan. Chapman has a distinct lack of pronation after release.
When you do not pronate, your entire decelerating arm action suffers. When you pronate, the arm naturally bends as it travels across the body. This bend accommodates the shoulder’s movement giving it a greater range of motion, which keeps the arm from banging the rotator cuff. It also disperses energy into the triceps.
Check out the differences between Chapman and Johnson/Ryan. Notice how straight Chapman’s, arm is. You can see the stress on his shoulder.
In case you think this is just a style issue, here’s another example. Brandon Webb had a very promising career, until shoulder issues sideline him.