Pitch tunneling seems like an impossible skill to teach without a fancy slow motion camera and advanced technology like Rapsodo or Trackman. But we experimented with using a L-screen and a couple PVC pipes and had success. We got the point across to our pitchers and they seemed to feel the difference quicker between pitches they release very differently with the visual target of throwing between the pipes in place.

Below we have two athletes miss high with a slider and a fastball above the top PVC pipe and then execute the same pitches between the pipes. The visual aids help them keep the ball on the same path longer while approaching the plate. They get visual feedback from the pipes and audio feedback from the catchers letting them know they looked the same for a longer ball flight.
Above, Video 1: Slider misses high above the pipes, Video 2: the Fastball and slider stay between the pipes
Above, Video 1 The Fastball misses high above the pipes, Video 2 the athlete makes the adjustment and throws both fastball and slider through the pipes creates a much stronger tunneling effect.
We had our athletes with very different arsenals attempt the constraint and all achieve the tunneling concept with relatively good results. The biggest feedback was they knew they missed the strike zone sooner when they didn’t get the ball flight between the pipes. We adjusted the height of the pipe tunnel depending on the pitcher’s arm slot and release height. Lower target for ¾ arm slots and shorter guys, taller target for over-the-top arm slots and taller pitchers.
Overall the constraint seemed to work for all the pitchers, it’s not perfect… they will hit the pipes and miss the target but when they get through the tunnel the pitches look similar for a longer period of time approaching the catcher. Most programs have an L-screen and PVC pipes are cheap, so we believe it’s a great constraint to help pitchers make adjustments with any pitch they struggle with. Once you find the right height for the tunnel, the pitcher can adjust accordingly with minimal verbal cues.
-Dillon Moritz September 20, 2023