It's true that color doesn't affect the properties of a ball almost at all. I am a Mechanical Engineering student with an emphasis in Polymers/Coatings, so I've got a little bit of background in plastics production. The color is added to the polymer during processing, and coloring plasticizers are chosen so as to have as little effect on the polymer properties as possible. If there is a difference it is because of the material or the processing methods, NOT the color.
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Rookie of the Year, 7 years running. Wait, What?