There are many things that effect the forces applied to a bowling ball. I like to consider the release as a combination of force vectors. Imagine the direction and the strength of the forces being applied to a bowling ball at release. Try and represent these forces with a directional vector and the strength of these forces needs to be considered as well. Thinking only of the directional forces being applied to the ball is the first step.
Lets consider how our physical game effects the directional forces applied to a ball.
When we understand this it is easier to understand why certain styles match up to certain conditions. Before we even think about how the hand influences the directional vectors lets consider the approach, because this is undoubtedly one of the most misunderstood. The approach consists of a forward movement to the foul line and the tempo of this approach is just as great a consideration. Obviously this forward movement of the approach provides a forward directional vector. This is part of the release.