Ok 2 things you need to understand when running a community strengthening exercise.
1. The top players DO NOT grow the community. Having said that they do come into play (read on). They aren't going to add anything you don't already have. They're clearly dedicated to some degree already. It's the new and lower tiered players that increase the community. This is where you need to facilitate your top players. You use them as a tool to grow the competition.
2. A games strength is based off 2 main things. Competitiveness and popularity COD4 is one of the most competitive, popular titles. CSS is probably the most competitive. League Of Legends is very popular but not so much competitive. See the trend? All the big games have one of those factors.
So 2 ideas briefly thought of.
Elite Captain and Coach.
You choose 2 players from each top team (maybe top 12 to give you 12 teams). One should be the 'smarts' and one should be the 'skills'. The one with smarts becomes the coach and the one with skills becomes the captain.
From there these 12 teams then get given a lower tiered team and become there captain and coach. The captain plays, the coach doesn't. You have intervals at switches and the coach can give advice. The captain should be calling the shots during rounds.
This involves top teams and lower teams. It gives the lower teams a better understanding of the game and a chance to win some cash. Same for the coach and captain. They can lead a side to victory and win some dosh.
Top teams get duds :P
You choose the top 6 (or h/e many) and they field 3 players. The other 2 spots and filled by up and comers via a lottery draft. Best side gets last pick, lowest gets first etc etc. This again allows for new players to get a chance to play with better players and win some cash. It also forces your top teams to teach these guys (and adapt to them) while also trying to land some cash.
Both pretty simple and obviously need to be worked on but I do think both would work better than the way you have atm.