The reason for the dimples is specifically because air moving around a spherical object creates a zone of lower pressure directly behind it, as the air cannot completely envelope as it moves -- and this slows the ball down, and decreases the range and speed of the ball dramatically. The dimples help to break up the air moving over the surface, and create a series of trailing vortices that disrupt the lower-pressure zone and allow the ball to fly to its maximum distance.
If I remember correctly, that is.
"And lo, let us open up into the holy book of Proxy2..." -genk
His pot is blacker than his kettle!