Air moves evenly around the smooth ball and creates a large suction at the back, which holds the ball up. Dimples make smooth air turbulent. The thinner that boundary layer, the lower the drag, and the farther the ball travels. Dimples have the same purpose as wings on an airplane, which are designed to make the boundary layer an ideal thickness to help keep the plane moving. While a ball's spin actually creates its lift, dimples can increase lift and affect its amount and direction, particularly at lower speeds.
Stitches rough up the surface air and enhance the baseball's lift.
Settling Differences Dimples come in numerous sizes and shapes. Each has an affect on ball flight, allowing you to adjust your shot trajectory for different playing conditions. Here is a general list of dimple traits, how they affect your shots, and when you might want to play them. They need to be properly sized and shaped. The USGA imposes no standards on dimples, which allows manufacturers a free hand.