Hi!
As far as I know, the stats just go with the player ID. The name displayed should be the last one you used. For example if you're playing as Stinker and later play as CleanMan, the name displayed in the stats would be CleanMan and they would show the summary of the games you played with both names.
Now the problem with "PlayerX" arises whenever you lose the connection to the game and the server notices only after you rejoined again. When rejoining in this case, the server will see that there's a player with the name Stinker on the server already (it didn't see you disconnect yet) and assigns a new name, which usually is Player, followed by a number.
We had this problem quite often lately when the game clients of players crashed while playing Freon on FunHouse #4.
I must see what I can do about the crashes. I have a notion that it might be an incompatibility problem with some mutator or server actor. Needs some testing though...
As for you, it should be sufficient to play a match as Stinker again to get your name back in the stats. Just start your game, see if the name in your settings is still correct and then play on FunHouse.
Coco.