recently played a tournament where my last round opponent had a provisional rating based on 5 games. looked him up in the members page but no information of him playing any tournaments except the one we just finished. what was the provisional rating based upon? was it just a tournament that hasn’t been entered yet?
Your opponent has a FIDE rating, and his US Chess rating was initialized using that, based on 5 games. Players with a FIDE rating higher than 2150 get an initial rating based on 10 games.