Originally Posted by
Cefiar
hold: They're related to how many games that person has won or lost, within reason. That determines their rank (higher points = higher rank).
ie: If you're well down the rank and constantly being pitted against the top 10-20 ranked people, and you've not got teams that are absolutely top notch (ie: exactly the right skillsets, relics, sharded completely, perfect talisman sets) then the chances of beating them can be extremely low. Now imagine that you refresh your opponents list, and those same teams (or similarly ranked ones) are there.
Same goes in reverse. If they're well below you, you'll probably stomp them flat without blinking, pushing your points (and rank) higher.
The points can be a bit bogus if the person who has lower points decides not to put much into the arena this week (esp if they leave a good defence set up), but when there's significant difference, it is likely to be very hard on the lower team and easier on the higher one.