General Question On Strikes Of Capped Bust Half Dollars

I've noticed on a number of Capped Bust half dollars that there seems to be what appears to be wear on the reverse that slides down from the rim to almost the center at the eleven oclock part of the coin almost always obscuring the first few letters of Pluribus.

I've seen it enough to think it odd for coincidence type wear and tear and was wondering if this is a sign of a common weak strike of the coin?

Thanks,
Terry McManus