how many pitchers are in a rotation ?
Common pitches include a fastball , which is the ball thrown at high speed ; a curveball , which is made to curve by rotation imparted by the pitcher ; a change - up , which seeks to mimic the delivery of a fastball but arrives at significantly lower velocity ; a splitfinger fastball , which attempts to mimic the delivery of a fastball , but has slight topspin rotation allowing the baseball to sink as it approaches the batter due to the position of the index finger and middle finger being " split " on the baseball ; a slider , which is made to curve laterally by rotation imparted by the pitcher ; a knuckleball , which is held either by the knuckles closest to the nails or by the nails themselves allowing the pitcher to throw a baseball with little or no spin on the ball allowing the baseball to move in any direction ; a Vulcan changeup , which seeks to mimic the delivery of a fastball but arrives at a significant lower velocity due to the pitcher holding the baseball with the middle and ring fingers slightly apart ; a circle changeup , which is held in the palm of the hand with the index finger curled around the side of the baseball , allowing the pitcher to mimic the delivery of a fastball but arrives at a significantly lower velocity .