A golf ball includes a unitary core having an outer surface, a geometric center, and a soft transition region adjacent to the outer surface. The core is formed from a substantially homogenous rubber composition. The golf ball also includes an inner cover layer and an outer cover layer. The soft transition region has a thickness of up to 4 mm and a negative hardness gradient of up to 15 Shore C. The unitary core has an overall negative hardness gradient of up to 20 Shore C.