Hi Jim666,
If their initial rating was significantly lower than their opponent's, or if they played many games that day, this will be the case. 
For more detailed information, please see FlyOrDie's rating table at  

https://www.flyordie.com/games/help/rating_system.html

 
Kind regards,
John

Hi, 
There are numbers on the left and right sides of the game. Each area on the board counts as 1 number. When you collect all your tiles, this number becomes 0. If the total difference between you and your opponent before your last move is between 0-10, if the person gives up, they get rid of the mars(gammon).

The details of this may also vary depending on the dice rolled by your opponent. (Distance of your stones to the collection area)

Enjoy your game.