I've ready a few things about what people are seeing in olympic swimmers. Oddly, it doesn't match what I am seeing in the same swimmers.
Some prominent things I notice...
-The incredible quiet & still ness that occurse underwater. Not that there is no movement, but there is minimal movement...just enough to get it done
-Glide/stillness out front. EVERY swimmer in every stroke enters and pauses in front...there is a moment or more of stillness. Maybe 1 swimmer in every 3-4 heats moves through this moment without pausing.
-Many cases of the slowest tempo being the fastest swimmer, especially n the breaststroke
-At least one case of a single kick fly that no one commented on in the mens 200 fly prelim, 1st heat winner
-every swimmer in every stroke swims on tracks...arms are parallel to the direction of travel with not only no crossover, but nothing even close to crossover. Arms dead parallel.
-Streamlining is prominent in every stroke as well.
-arm entries in freestyle...all of them spear and extend forward underwater, and all of them have a full extension up front accompanied by the pause. Their extension occurs under water not above. No one does not extend, but many recreationals wimmers lack the extension.