i'm not sure, but my guess would be that in GW and WUSL's case they're getting more apps from higher applicants due to their change in rank. People at a certain level are likely to throw GW and WUSL an app to try and get a top 20 acceptance (and not have to go to minnesota). I don't know that there's any real cutoff between 21 and 20 or 19, but GW and WUSL have been hovering right around the 20 mark for a while and just made the under 20 cut.
I don't think these schools will benefit much from this except where they give money... which i think is why GW has been aggressive at giving away money... it'll solidify their position in the top 20.
But maybe i'm just making things up.