Pitch tunneling in baseball is when two pitches look the same for most of their trajectory towards home plate, but then move in opposite directions. Pitchers utilize pitch tunneling to try and fool batters, by throwing a fastball first, then throwing a similar looking offspeed pitch to throw off the hitter. I created a metric that identifies how similar two pitches are. I used this metric and found that the more similar a fastball and then a slider in succession are, the more likely a batter is to swing and miss at a pitch they shouldn't be swinging at. This supports the theory of tunneling: the more that two pitches look the same until the tunnel point, the more effective a second pitch offspeed (curveball or slider) will be.