I would suggests few things:
1) introduce the "invite" program (the same of HT), to invite your friends in your own conference/league. It's much more intriguing to invite your brother in your conference than anywhere... just because you can be sure you'll beat him! ;)
2) introduce a 2-level system for evaluation reporting. Level 1 should be quite simple and immediate to be read and comprehensible to people with minimal understanding of basketball, providing immediate guidance to identify most relevant isssues. Level 2 should be for most proficient users, with enhanced reporting, and - if not possible otherwise- capability to easily download and import raw data to excel/open office. I will post a more detailed suggestion later today. As of today, statistics are too fragmented for advanced users, and too complicated for newbies.
3) provide a welcome kit for newbies. I see the same questions replicated over and over, although in Italy at least we have the "bbguida" with lots of suggestions. Let's say it could be a "quick start" guide, plus some key suggestions for newbies, inviting them to enter into forums (I agree with you, community is the key value of BB!)
4) improve transfer system for quicker and easier search of players (including potential and height, for instance)
5) I agree with suggestion of improving supporter tools, including block-notes introduction
6) extension of free supporter period for the first month - in one week I understood the value just because I was supporter in HT too
7) expand live reporting to enhance your experience - with a more realistic reporting based on more information (i.e. I would like to know whether I just scored a double-double) and more enthousiastic sentences (I think it's just a question of extending current lists, based on community contribution of course!)
8) introduce formal tutoring, to smooth transition-in period to newbies. All people in community with at least one season of experience could/should be assigned as tutor to newbies, having the capability of seeing player information to easily provide first days suggestions (let's say up to 10 days since the beginning)
Apologize for the length of the message, hope you'll appreciate my enthousiasm!