I just looked again and they do appear to be relatively big, however I do recall reading neighbors thought vandals perhaps moved it and IIRC MSM was reporting at one time it was possible for a person to move it..
I just don't know how there wasn't evidence of a rock that size being dragged from that point to where the jeep went off the mountain...JMHO
I saw the interview with the homeowner last night. He said they thought vandals had pushed the rock over the edge, which would explain the rock being missing and any marks or tracks that were present. He even went as far as to say he went and looked over the edge to see if he saw it, but could not because of the leaves.
Also, do we have info that proves the rock went over with Gail??? Being in a Jeep, she could have gone over, NOT taking the rock with her, and then a vandal could have been the reason the rock was moved. More coincidence, yes, but true life is normally stranger than fiction.