Well you've made your point. These imges don't handle well with noise reduction. They look too glassy/plastic. I think the problem goes back to the original image - motion blur, maybe focus, maybe resolution, and the general challenge of capturing images of swimmers bathed in water.
Among sports, swimming would rank high on what I'd like to shoot (beautiful action) but low on what I would try to shoot because of the very difficult conditions and my very limited knowledge of the sport.