As this has developed into a more general discussion, I was thinking recently we have the worst of both worlds with the current level of injuries.
They are rare enough that short, top-heavy rosters are the optimal way to build teams. But this means when injuries happen mid-game it is often the deciding factor, which is completely unrealistic and also ruins the gameplay.
So in my opinion injuries should either be turned off or turned up. The pros and cons of the former are obvious. The latter also works because it forces teams to carry deep rosters, as you will encounter multiple injuries through a season. But it means if you do get an injury then the replacement will also be pretty good, so a mid-game injury doesn't auto-lose a cup final or play-off game. This is more realistic but much harder to balance the game overall.