There is a lot of important information contained in Danny Ainge's tweet below. First of all, apparently it was no contest between NBA Skills Trainer, Jason Smeathers, and Aussie athlete and Celtics rehab manager, Steve Mount. Swimmers need muscle, and Jason doesn't have any. And being so lean, he probably sinks like a rock.
Gordon Hayward didn't take part in the swim meet, but his photo tells me two things. First of all, his left ankle is still somewhat distorted from the fracture, dislocation and surgery. I am no physician, but the distortion does not appear to be overly significant considering the extent of the injury.