While 'pitch tunneling' is a thing I don't know about trying to train it, there's a lot of unanswered questions. How big should the tunnel/ring be, 1ft, 1.5ft, 2ft? And how far from the pitcher should it be? Does the pitcher aim for the tunnel or at the plate with the tunnel just being there for reference?
Yeah, I almost prefer the opposite. Put something right down the middle and try to avoid it. I'm not really sure how tunnels will help much. Would be kind of fun for a while though.