First I want to state, I like the Fargo system.
Almost two years ago I beat a guy that won the tournament I was in. It was the first round and we both played bad.
I did make it to the top ten in a field of 79.
I have not really competed since then for medical reasons.
My Fargo has gone up over this time because people I beat have gotten better.
I am a 5 in our TAP league, yet many of our 6's are 20-30 points lower. in Fargo ratings.
If some one I beat "back in the day" ends up being a pro, will I be punished forever?
Again, not knocking Fargo, trying to understand.
Also I do not consider "sandbagging" as an issue in this league. I have played and been around it for many years and know most of the players.
It is actually a misconception that a player's rating goes up because former opponents improve. Sure you can concoct hypothetical scenarios where this is a thing. But in reality it isn't.
Imagine a situation like yours, where you played, say, 8 matches in a tournament a few years ago and got a preliminary rating of, say 550. And now, two years later, without you playing, your preliminary rating is 600. Does this mean my opponents got better? No, it doesn't. It means FargoRate understands better how they play.
Let's dig in
Say you played 8 matches and had the following scores
6 - 3 against a 450 with 500 games in the system
6 - 3 against a 400 with 500 games in the system
6 - 3 against a 500 with 500 games in the system
6 - 3 against a 450 with 50 games in the system
3 - 6 against a ??? with 0 games in the system
6 - 2 against a ??? with 0 games in the system
5 - 6 against a ??? with 0 games in the system
6 - 4 against a ??? with 0 games in the system
For the first 3 matches you were 18-9 against opponents averaging 450--so that's you playing at 550 speed. The next match you also performed at 550 speed, but the system would not count this as much because it has a weaker understanding of how that opponent plays. The next four matches are ignored because the system has no basis to assess your wins and losses. But it still remembers these games.
As time goes on these opponent ratings drift a little, but the major effect is the system starts to understand how those opponents play, all of them, and finally is able to interpret those games you played before.