From the RR4W website - Rating System Explanation...

Trails are rated for difficulty in order to help you enjoy your visit. Ratings are not meant to be a challenge. We know you may be able to out-do the system on a good day, but in a crowd of about 50 vehicles, we hope everyone will be equipped to deal with the obstacles.
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It seems the new system is going to take some time to adjust to for all of us.  I just led a trail at SW Crawlfest that we rated as a 6.  They are running the same trail in the Winter on the Rocks event and have rated it a 4.5.  When I compare the trail to the ones rated 4's and 5's in Moab I think there is reason to believe it is a 6 trail.  The entry to the trail is a 160 foot hill at about 40+ degrees.  This hill has mud on one track and slickrock on the other.  No bypass.  Without lockers this can be a very hairy entry.  After mudding up both passenger tires, the 45 degree downhills get a bit slimey, also.  Of course, in the middle of the summer when it dries out, it is much easier for an open vehicle, but our events are in winter, and there is mud on the hill.