Also, the PG weighting system rewards large recruiting classes. If a program doesn't have a lot of money to throw around in a given year, or if it doesn't project losing a lot of upperclassmen (graduation, draft, transfers, etc.), it can draw a bad ranking and yet, years later, be doing plenty of winning.
JMU is probably up there simply because the new coach brought in a large class.
Conversely, some of those bringing in large classes get highly rated, but (a) that's in part because they're losing upperclassmen and not always for healthy reasons, and (b) that's also often in part because some programs sign top pro prospects that they know full well may never show up on campus. I know, for example, that UNC went several years in a row after its multiple years in Omaha, recruiting big but then losing 3-6 members of its incoming classes to the draft.