When I have used decoys I always take a couple small twigs or something and poke in the ground on both sides of their tails. Give them room to sway a little in the wind for realism but it will keep them from spinning all around. But my thoughts are if they came in that close that fast before spooking, you could have whacked one with out the decoys being there at all. Its a coin toss as to how they will react to them.