If I were to assume anything, it would be that medical budget determines your player's degree of success at reclaiming lost ratings points to injury. My medical is set to 20, for two purposes: 1/ making sure that my injured players "make it back", and 2/ using the "bug" if I need to.
I already have owners in my league running high training and low medical, with the understanding that as soon as one of their players gets injured he becomes trade bait. Those players are ruined for further use, BTW... but who cares as long as they're not on your team, right?
The bug is part of the incentive to use the medical budget. I agree with Mike, change Injury Recovery and more owners start using that money to jack up IFA prices.