This is no longer just about injuries. I’m not sure if discussing this here is slightly off-topic, but since you asked, I’ll share some thoughts.
We have to recognise that many of BB’s systems are quite old and need optimisation. Moving a team from a 7–8 man rotation to a 10–12 man rotation is not something that can be achieved by changing just one system.
First of all, player salaries increased significantly after the youth system was introduced, but neither club income nor the existing minimum salary cap were adjusted accordingly. As a result, it’s very difficult for teams to afford a larger squad. In my opinion, given current training speeds, the minimum salary cap needs to be raised substantially.
Finance is the core issue. BB has neither a max salary nor a team salary cap, so it’s already possible to have, say, five all-star players on one team. Under these conditions, as long as you’re willing to run at a loss every week, there is simply no need to keep lower-level players on your roster.
Secondly, as I mentioned before, we need changes to the stamina and injury systems to encourage managers to use deeper rotations. For example, if you only have 7–8 players, and your starters play 40–44 minutes every game, their stamina will drop over time due to weekly fatigue. This will naturally lead to worse performance and an increased risk of injuries. If you cut their minutes to 28–32 and rely on the bench, fatigued starters can recover their overall fitness over the course of the season and lower their injury risk.
This is similar to real-life basketball, where pseudo-benches and strong sixth men may still play 20–30 minutes a night and have a real impact on the outcome of games.
Which brings me to the current game engine. It doesn’t allow detailed minute management. Player still needs to play 48 minutes to receive full training — a mechanism that many consider outdated. I won’t go into detail here, but in short, both the match engine and the lineup system must support and encourage more rotation.
I haven’t thought too deeply about this yet. Mostly, I doubt BB has the resources to make such complex changes. And I have no idea what direction the new management plans to take on this front.