Slider
A slider is a pitch halfway between a curveball and a fastball. When thrown the slider breaks laterally and down with more speed than a curve ball but less speed than a fastball. TThe release technique of a slider is between a curveball and a fastball. The most notable difference between a slider and curveball is that the curveball delivery includes a downward yank on the ball as it is released, in addition to the lateral spin applied by the slider grip. If the pitcher is snapping his wrist as he throws, and the movement is more downward than sideways, then he is probably throwing a curveball or slurve, and not a true “slider." Ted Williams once said that a slider was “the best pitch in baseball.” Whether or not that's true depends on a lot of things, of course, but the slider is certainly an effective pitch for those who can throw it correctly. The key with the slider is to hold the ball slightly off-center (on the outer third of the baseball). Slightly cock your wrist, but not stiff. You need to still get good wrist-snap upon release. If your wrist is slightly cocked to the throwing hand's thumb side, your wrist-snap will enable you to have the pitch come off of the thumb-side of your index finger, which, in turn, promotes good spin on the ball.
