This is the ridiculous thing about this game. You do careful preparation and make sure your team is in top condition for a match and get shafted. Go in with poor condition and/or tactics and the team waltzes it, except when you do it deliberately...
I always played with my player condition at just 30% above. I experienced no injuries and manage till stage 8 but unable to beat France. So I guess I am one of the lucky one.