But... if there was a way of making injuries fair and realistic, they should be definitely linked to game shape... higher levels of game shape should prevent or stop injuries (level 9 should never lead to injury, level 8 extremely rarely, level 7 less rarely and below 6 injuries should happen often)... mastering game shape is hard and should be rewarded
Unless you have just bought a player it's near impossible to have someone in less than 7 GS, and most players are in 8-9 GS all season (after the first couple of weeks). GS is very easy to manage for two games/week, it only seems like a challenge for elite teams trying to win three games every week. But even then I rarely see their players in low GS. The above is basically just turning off injuries.
I would like to see a little more variance in GS updates, but I suspect that would be a minority opinion
The higher the level of staff, the more exponentially expensive they are and the less exponentially they give you back.
My understanding was the difference in skill between a level of staff is a roughly linear improvement, although I'd have to double check that.
Salaries seem to also be linear, roughly you might pay $5k for a level 2, $12k for a level 4, $20k for a level 6 doctor. Higher level salaries do increase at a slightly higher rate, but the initial fee for non-coach staff is very small so you can just replace them more often.