I think WCKY changed from a three tower dogleg to a four tower parallelogram. That explains part of it. The 0.5 mV/m 50% contour is considerably smaller due to the newer skywave prediction methods, unless it is further south like WWL and WSB. Stations just outside that contour are only supposed to be a few watts close by, or less than 250 watts directional somewhat further out.
Well protected former Class II-B, III-A, and III-B, signals sound like graveyard freqeuncies when the local station is off or outside the service area, but the interference should be only 100 uV/m to 300 uV/m RSS. There are usually several low level interfering stations that give the graveyard effect. High NIF stations, when off the air, get as much as 1 mV/m 10% skywave from one or two stations, making it seem like a clearer channel when the local is off the air.