give it a try
95 for the injury frequency
15 for the injury severity
lots of fun managing your squad when you can have around 3-5 injured players during a season, although it can get pretty gutted feeling when your star player or gk get ACL injuries in training lol...
on the other hand it makes for a more interesting matches because both your players and opposition's can get injured from hard contacts, most of time they can limp back into the matches, some other time they could even get healed in the match, on the worse day they can appear to get limped then healed and only to be really injured after the match
a pretty cool game changer in regard to dynamism in matches
further bonus is that because you can actually injure opposition players in a match, it may make your play far more brutal because you want to revenge the AI lol, before tweaking the injury sliders I rarely get a card in a match, now I could get 1 red card in every few games and 3-4 yellows per game because... well you could guess why lol...
seriously, give it a try, it's more realistic, fun and game changer this way; don't be scared with the 95% injury frequency slider, it doesn't mean your players would 95% get injured after a match, you could also tweak the severity to suit your taste.
ps, I'm not sure if those sliders affect fatigue though...