that would be my 1st guess
Wounded would be scared and more than likely dive and try to swim away... you know, that thing where only their nostrils are out of the water and all you see is a little wake.
They are just that dumb. A few years ago I took my son and a few buddies with their dad to a big pond. I went with one dad to one end just to get the stragglers and sent all the boys with another dad to hunt the dekes. Like somebody else said, a group decoyed and they dropped 3, came to us and we dropped a couple, flew back to the dekes and they dropped a couple of more, then came by use again for us to pick up our last 2. On the way home my son said, "Ya know dad, there is a duck dumber than a teal."
Last year we passed on a group cuz we already had our limit of them. So they just hung out with their new plastic snobby buddies. A group of greys came in, we get up out of our layouts and drop a bunch of them. All the booming and commotion, dux dropping dead all around them, dog in the water... and they just swam around like nothing happened.