I think a different point system is in order. You want more players and you want them to play as often as they can. The way to encourage players to play is to reward them.
If the players do badly they go down in rank. Soon they will get discouraged and mad at SMG. Not only that, if they keep trying and can't rank up they will eventually quit and leave and never come back.
Why don't you make it such that points only ever go up every time a game is played? 1st place - lots of points. Last place, minimum points, and the rest is in between.
That way the more you play, the higher your rank. The better you play, the faster you go up. But if you suck but you play 24 hours a day 7 days a week for a year, you can eventually go up too.
This way dead accounts will also slowly get flushed out of the system instead of the leaderboard having all the ones that aren't active.
This will also solve the problem of highly ranked players not willing to risk their precious Grandmaster level and basically stop playing.
This is a great game, I wished more people played it and gave you guys their money.