1823 Large Cent, Odd Wear Pattern?

I got this in a bunch of coins purchased from a coworker's boyfriend, the wear on it is kind of strange though. Much of the coin is still relatively strong, while the date is worn nearly flat. There's also a pretty nice dent at around 8:30-9



When held in the light at an angle, the date is still readable:



Any idea what might have caused the uneven wear? I'm thinking it has something to do with the source of that dent.