It might be that I'm simply myopic so maybe you could expand on that grey area you mentioned with some concrete stuff, if you had any in mind.
1) The training system needs to be looked at properly not patched here and there. You need make it a little easier (maybe allow for 1 player to get training no matter what position he plays and no matter how many minutes he plays) on people and it needs to be faster at least at the beginning when you start training guys.
2) It would also help the sense of progression if training improvements were more visible than just pops when you break the barrier to the next level. You can do this openly with bars OR you could do it more covertly with the possibility of comparing the skills and sublevels to other groups of players (in your league, country, worldwide). So you know that today your PG is in the top 20 percentile for OD and in 4 weeks he's in the top 17 percentile
3) Providing advanced stats
4) Make arena building easier on the new managers (maybe a discount, like 20% off for 3 or 4 seasons)
5) Providing the possibility of customising your team. Such as allowing to change team shirts, the team stadium. As it is what do we have? The avatar? Heck for all I care you might as well code cheerleading into the game and provide an effect similar to the PR specialty if the cheerleaders a manager designs are particularly nice.
6) Design more ways for managers to interact outside Forums and the game chat. Perhaps taunts before a game
7) Better visibility of what's going on in the forums when there are new messages that may be of interest and you are not even signed up to a forum
8) Give more flexibility in organising parallel "fan" leagues also for non suporters. So if I want to organise a friendly game with a friend I'd love to. If I want to organise a league open to D2 teams to determine the best D2 team playing on Mondays I'd love to
9) Let managers to different leagues manage one or more bots (no roster changes of course) in a different league for free?
I can think of a lot of changes that could potentially make the game more engaging for people and that could give a sense of progression for new managers...