I haven't read the bug thread yet,
When I got my first injury that lasted more than a game, I still had Level 1 Max Payne. I rushed over to hire a new doc, and that week there was a Level 10 for about the price of a down payment on a BMW. I went a couple of weeks before I could get a new doctor. The injury simply did not heal.
After I got a doctor, the injury started to heal. Unfortunately, I had a swarm of injuries (I had 6 players out at one time)., so I also got some experience with the effect of age on recovery. It really did seem to be similar to HT.
It does appear that in BB, when an injury is +N, it really will be close to +N before a player reconvers (you don't did the miracle cures of HT), and a 24 YO heals about like a 31 YO in HT. In addition, BB has a shorter season than HT, the teams are smaller, and you have two league games per week.
A 3 week injury in BB is (1/5)*(6/22) = 5.5% of league playing time.
(a player is 1/5 of the team, and he is out for 6 of 22 league games)
In HT it is (1/11)*(3/14) = 1.95% of league playing time.
(a player is 1/11 of the team, and he is out for 3 of 14 league games).