Seam Shifted Wake

Two forces that change the path a pitch travels are gravity and Magnus force. Gravity causes a pitch to accelerate downward, which causes the impact to grow as the pitch approaches the plate. Magnus force is movement of a baseball caused by transverse spin of the baseball. These two forces result in a theoretical expected path for the baseball. However, on the field unexpected motion happens, especially with elite pitchers.

Some pitchers have a cutter, sinker, or changeup that starts to break as they cross the plate.