I'm definitely a novice, but I guess I don't understand how you can think it's been sanded down. It certainly looks scratched, but the flat surface is even with Lincoln's face and the coin has the same thickness all the way around. Wouldn't sanding make it thinner on that side?
It looks to me like someone drug it with their shoe across some asphalt in a parking lot. It might excplain the uneven grinding.
I don't necessarily think it was sanded, but definitely PMD. I agree with gary that it was drug across the parking lot or something similar.