Anyone who plays HD or GD is familiar with the types of injuries that occur in those games. A guy will get hurt and be out for a certain amount of time, but the injury is represented as an amount of wellness (from 0% to 100%) and once a player's wellness reaches a certain threshold, you have the option of putting him back into the lineup, albeit with a diminished playing capacity (and presumably a greater risk of reinjury or serious aggrevation of injury).
I've always felt that the injury structure in HBD was a little stiff; you're told exactly how many days a guy will be out, and he is totally unavailable with 1 day remaining and 100% the day after that, with no grey area at all. Obviously this is quite unrealistic; in real life, a guy might play at 90% after an ankle sprain, or a guy might rush back to play in an important series and get reinjured.
So I think a fairly easy way to implement this in HBD is to just reassign some injury components as a function of the player fatigue rating. In other words, say a player breaks his leg. Maybe he's out for 100 days, and for the first 85 or so days, his fatigue is at 0%, and he can't play. Then you get an e-mail from the trainer saying "Good news! John Smith was cleared by the team doctor to play, but he was warned that the injury will take another 15 days to completely heal. It's your call, but John says he is feeling about 60% right now and eager to get back on the field" (maybe the earliness of the e-mail depends on makeup and patience, so the e-mail comes earlier from a guy with great makeup). After that point, his fatigue % increases rapidly over the next 15 days, so that it hits 100% by the end of the injury time, but if you decided to start playing him with 5 days still remaining, maybe he's at 90% when he takes the field.
For pitchers, it would be the same way, except their "injury fatigue" would be the new ceiling level for them. So suppose a pitcher comes in with an injury fatigue level of 60%. He pitches and his fatigue goes down to 30%. His fatigue level then increases as it would if he had pitched normally (let's say 24-25 points per day for a 25 durability pitcher) but it stops increasing once it hits that injury ceiling number (probably something a bit higher than 60% since it would occur a couple days after that point).
This could also allow for the implementation of "nagging" injuries, which would make the game much more like real life. A guy with a calf strain or sore arm might be playing at a slightly diminished capacity for months. You can either keep playing the guy at a dminished capacity or rest him and allow the injury to heal much more quickly. There could even be an "elect for surgery" option for certain injuries where a guy could either be at 85-90% for the rest of the year, or you could lose him for a month and get him back at 100%; that could be a very interesting feature.
Thoughts?