My teacher, Shimizu Sensei, emphasizes frequently that ukemi has to be done together with Nage, and not neccessarily silent.
That means, itīs no good if Uke - coming to the point of being thrown - jumps off by himself and then landing on the mat like a feather. Because this is likely to result if people are trying to achieve a silent ukemi. But the connection between Uke and Nage is disrupted, Uke is performing ukemi on his own. Focus should be on acting together, so itīs not only Nage who has got to harmonize and blend.