Yeah, execution was lacking. Slaine's explanation was that the funnels were designed to surround the enemy, making it hard to shoot them down because they are all over the place and shooting at you from different directions. However, the entire fight was the funnels shooting at Slaine from behind because he was dashing away the whole time. The supposed advantage of the funnels were never really displayed.
If I had directed that, the funnels should have been moving in different directions and covering a larger area, trying to corner Slaine as he zipped around. Then Slaine would use his dumbass crystal ball to somehow avoid being cornered and then hide into that tunnel. Then it would make perfect sense that he would be able to shoot the funnels down because they are clumped together in one direction instead of trying to surround him all the time.