IDEA: Make 3 types of injuries. Severe injuries are what we see today, but a lot less frequent. Minor injuries turn to a "de-buff" and will drop a players skills. For example, Player A can get a medium wrist injury lowering his Jump Shot, Jump Range, Handling, Free Throw and Stamina by 2 for 2 weeks. Player B gets a minor ankle injury and lowers his Stamina, OD and ID by 1 for 1 week, etc. (Or a stomach virus lowering stamina).
This would allow you to continue to play injured players (sometimes - when not severely injured).