ESPN Stats & Information's Courtenay Harris put together an interesting blog on Colby Lewis' slider, complete with heat maps.
The bottom line: Lewis' slider location was solid on May 16 when he shut out the White Sox. And when he's had success this year, most of it is because of his ability utilize the slider to both right-handed and left-handed hitters.
But take a look at Harris' numbers. They are very telling. (And those heat maps are really cool, too.)