Felt and Fuzz

The fuzzy felt on a tennis ball is not decorative - it is aerodynamically critical. The felt increases surface roughness, helping the boundary layer cling and strengthening spin effects.

A smoother, more worn ball tends to fly faster and curve less dramatically. Players often choose the newest, fastest ball for a first serve. For a spin-heavy second serve, they may prefer a more worn, fluffier ball because its slower flight gives more control while the spin helps it clear the net and drop in.