Understanding RPI

I've been pondering the past few days how DePaul could open so high in the RPI yet not get any votes in the poll.  I finally found an explanation of how RPI is calculated (at least for basketball) on the NCAA Web site.  Assuming the same RPI calculation, more or less, is used for soccer, it appears DePaul has been rewarded for playing a very tough schedule, even though it hurt their overall record (and their visibility among pollsters).  On the face of it, for example, DePaul only has played one opponent that was ranked at the time, and they lost 6-0 to #17 Louisville two weeks ago.  But early in the season they beat unranked Northwestern on the road (granted, not much of a road trip), and Northwestern now is ranked #16 and, probably more importantly, #1 in the RPI.  It will be interesting to see how DePaul moves in the RPI as Northwestern itself moves.