So, BB2 has some issues with current bank system which make it difficult for more squishy teams to accumulate a lot of money in advance, in case they'll take heavy losses one day. There is a reason for that (to not allow overdog to buy too much inducements easily). We also have Aging rule active in some Leagues, which adds additional needs to constantly prepare substitutions for your core positionals so you would have another experienced one when the current star will retire.
We also have certain positionals in some teams which are not quite popular, because they are only situationally useful. Like, Assassins in Dark Elves roster, or some Big Guys. They are often not used at all as they may only be useful in certain matches, while bloat TV in all of them.
Idea: Each team gets short support roster for its scrub players (1-3 players long). Players put there stop being counted towards its TV, and cannot be fielded after match is started and don't get MVPs. Thus you can have said Assassin which you only need in your matches against elves and stunties, and keep him in scrubs for the rest of your matches; or you could have this goblin with DP which most of orcs team usually don't use, and keep him in scrubs for some very special match where you may need him finally. Thus all those interesting guys may actually see some fielding after that, bumping variety a bit.
Or you can buy certain positionals in advance with spare money, and put them there. In such case you should be allowed to keep more positionals of certain type than you are usually allowed by your team's roster (of course, you still can't field more than that)
So, for example, in leagues where aging is enabled, you could have 2 active Wardancers in your Wood Elves team, and one extra you bought after some time and put into scrubs. So you can sometimes field him instead of one of those active dancers, allowing him to earn some SPPs - thus preparing a substitution for your main dancers, as they will retire one day (or meet sudden demise).
It solves also issue with the cash limits - you can't use those money invested into additional players to buy inducements, so it's safer than allowing such teams to carry more cash without it being added to TV, from this point of view
This also will allow to put some of your valuable players in there if you have some worries there will be too much risk of them getting injuries in the upcoming match, substituting them with rookies, for example. So adds additional freedom for team management part of the game.
Players put into scrubs shouldn't be "aging" at the same rate as active players do, except for matches in which they are actually were fielded. After all, they don't see that much carnage as active players do I believe Aging deals not with their biological age, but more with amount of physical and psychological traumas accumulated So it's reasonable (and makes it more effective in preparing substitutions for your main players). Either matches where they were not active shouldn't age them at all, or age them at 1/2 or 1/3 rate as active players age.