Maybe you can try google adwords to get some new members fast.
It seems that you can learn which stats to upgrade by examening the "Play-by-play". Perhaps you should mention/explain this somewhere, faq?, because it's a bit hidden but a important part of the game.
I saw in 5.2.0 Alpha in the bottom that the link MyBaller.com is named "My Baller" if you rename it to something like "Online Basketball Game" then you'll probaly get listed better on SE's when people do a search with these keywords, which can get you interested members for free. Now you'll get a high ranking for baller, but that's not a word which is used alot and my will be ignored by SE's.
To help, and for the great work of creating a good topsite, I have a link to myballer listed at two of my sites for some weeks:
Each get around 500 visitiors a day, so it should bring in some members.
You better also place the meta tags keywords and description in your files which could be something like:
<meta name="description" content="My Baller - Free Online 1-on-1 Basketball Simulation Game">
<meta name="keywords" content="Online, Basketball, Simulation, game, coach, trainer, manager">