it is a bit of both, with a better doctor it would be very likely that your backup sf just missed the rest of the game.
Even the starting SF should have a chanche to survive.
i just can give you the table of the old doctor system, i believe they keep it roughly the same but you have to double up staff level now(so level 5= level 10 there)
(40900.10)But i also think that not investing in a better doctor, and buying replacements when someone injured is economical better atm for you.(as long hong isn't injured)