They may have already recruited them at some point or they know other coaches who have worked with them. Unlike high school recruiting, they have to vet these guys in a fairly short time frame.
I’ve said in the past that Rivals has underrated a number of our prep players. They tend to grade (or downgrade) most of them to 2 stars. Interesting that Golden, Norton, Rush, James, Nunnally, and Moore are heading out the door as 3 stars.