TC: I checked that last time and I think I am outside those 10% in all games. I think you will run into the issue that a significant number of those 10% are not playing anymore just sitting there. But otherwise I like the idea.
Here a hint how you can make it easier for potential participants: Obviously, because of your 10%-cutoff-point, the minimum rating needed is different for each game. You could list that minimum rating, so anyone can see right away if he falls into it. I found it rather tiresome to scroll through the full list to find out how many people are in total in the list, divide it by ten, and then find the rating of that position to see if I make it. If you do that once, you save everybody that work, and maybe get more players? Not me though...