@TerribleBPthrower posted:I would consult with a baseball specific trainer to make sure his body is structurally able to handle whichever program you choose. They may even be able to recommend something for his current body structure. At 125, I doubt something like Driveline would be good for him.
100% agree. In addition to a throwing program he needs to be doing an appropriate workout routine (core, legs, arms, etc..) for his age and baseball position. My 3 sons pre-dated Driveline but we followed a throwing regime put together by a baseball specific trainer.
One of the things I learned as a parent of pitchers (and applied to my sport) was that overhand sports such as baseball require a lot of mobility and flexibility especially in the shoulders and thoracic areas which meant working with different work out bands in many different parts of the body above the waist. Larger weights can be used for larger muscles below the waist, and the core needs to be strong.
The throwing program and the physical workout go together, and complement each other. As @TerribleBPthrower suggests, try to find a baseball specific trainer to help with both.
JMO. Good luck!