How do you throw a cutter in baseball?
A cutter is a pitch in baseball with action and movement similar to a hybrid between a fastball and a slider.  Perhaps the most famous cutter pitcher in baseball history, a closer from the New York Yankees named, Mariano Rivera, used the cutter exclusively all the way to the hall of fame.  The cutter is thrown like a fastball, but with a "football" throwing arm action where the pitcher's palm faces their opposing arm as they release the pitch.  Grips for the cutter can vary, however, the keys are to hold the middle of the baseball, cross the seems at an angle similar to a slider and be sure not to turn or twist on release.  With this approach, the cutter is a pitch safe for youth baseball as young as age 9 and can be effective all the way to the World Series as demonstrated by Mariano Rivera.