I run with $20 million in training and 0 in medical. In 20 some seasons I've had one catastrophic injury to an elite pitching prospect and a 1-2 injuries to BL position players that knocked them back a little.
What I have noticed is -
Most injuries are minimal.
Many of my injuries are to the legs. That doesn't knock back any hitting or pitching ratings. Can effect range and SB obviously, but haven't seen much that made me really cringe.
If I am gonna sign a big FA or draft a player I do keep an eye on health. But veteran FAs or pickups I really don't worry about health as much. As long as it isn't a long term commitment then I can ditch the player if he really gets hurt. And again, I haven't seen many injuries in those cases that really set me back.