You could always sell an injured trainee and replace him, though you're right, there is a lot of loss there. I don't have a whole lot of faith in the doctor portion of the team staff. If anyone has any figures on whether my lvl 6 doc is any better than, say, a lvl 3, I'd love to see them. I keep the lvl 6 around for piece of mind.
Well, as I recall from an IRC or forum post by a BB... in the old doctor system, the higher the doctor level, the more likely a "5 week injury" got washed out to something shorter. I don't expect they changed that in the new system. But basically, if you go naked on the doctor, a lot of the +1 and +2 injuries you get with your high level doctor could (but may not necessarily) turn into +3 or +4 or +5 injuries.
What I couldn't really factor into my numbers were things like STH, as I have no idea what type of STH loss could be expected while falling through divisions, how much a team of such tiny value would hurt the TV money for an entire league, what sort of merch revenue to expect, etc.
There were several newly demoted Italy II teams bitching in Globals about losing half of their STHs at the beginning of this season, and losing over half of their gross income from the relegation.