When someone concedes a game they should automatically lose.

[jgbaxter]

In games with 2 or more players if a player concedes they should be in last place, regardless of any possible victory points/conditions.

[Jest Phulin]

Which game did this happen where they didn't?
As far as I know, in a 2 player game, the player who concedes loses. In a more than 2 player game, conceding is not an option - to end the game before it reaches its normal end point requires a player being expelled, quitting, or a vote to abandon the game.

Or, are you referring to a situation where player A amasses 50 points, player B none, but then player A concedes and is listed first? Because that part really doesn't matter for ELO -- it's only wins and losses.