If the chest and shoulders get tight, the swing plane is going to be effected. As the ball swings back, it will swing and when the chest and shoulder have reached their limit of flexibility the upper body begins to rotate as well, when that happens the swing plane is redirected and in trying to realign it many things including hand position and release are effected. Arms and neck - Improper stretching of these areas is a sure way to injure yourself sometime in your career as a bowler. When I am talking about the arms, I am talking about all the way down to the fingers. There is a lot of strain exerted as the ball is released, and if the arm is not ready and pliable, things can snap.
Most injuries occur when a bowler is throwing hard at a spare or bowling before the body is ready.
As far as the exercises you do to accomplish these effects, I will leave that up to you. There are many and you might know some that I do not. Do not underestimate the importance of strength and flexibility in the sport of bowling. Take the time to think of the motion and the muscles being used and how one effects the other. This is the fourth and final installment of Rick's article.