at how it sits at the edge of the shroud, it is directed to basically pull across the radiator. With the shroud off, it pulls from anywhere BUT the radiator. The old 'path of least resistance' deal.
This is why fans have had shrouds for..... well at least the early 60s. Even FWD cars with electric fans have shrouds.
How you know the world is about to end. When you get a post from GR that says, "I dunno dude (n/m) - got rice? 22:09:37 08/30/00"