Hey, could you check out Cricket ball "swing" for me?
It's something of a mystery, the ball spins on a vertical axis, "normal" swing makes sense, (shiny side/rough side, ball swings in the direction of the rough side, if properly oriented) but there is a phenomena known as reverse swing, which happens after the ball is to worn for normal swing to occur.
Very few bowlers can use it, and very few good theories as to why it occurs.
Before anyone disses cricket, remember it's the only sport where you can aim at the batter, and get the variations of bounce to conk 'em into the bargain.