I wonder if there's some missing link here that the spec sheet isn't bringing across, like it gathering in the middle and then spreading at the hem the way a half-belt would. (In this case there's no half belt, but maybe this is happening at the top of the kidney panel, like my Johnson does.)
And you were right about the missing link. There is some pulling in at the little band above the kidney panel, that creates a bit of a flare. It´s not really obvious from the front, but the back-picture shows the effect quite clearly.