ok thanks! I tried it out with some reserve players, and they really get injured easily when they have poor condition. I always try to keep my main men above 85%, and they seldom get injured. I could not see this pattern with the fitness values. I always only train Defense or Offensive for a player, never fitness. These players don't get injured more often than players, who I buy from the auctions that have high fitness values.

So now there is still the question with morale. Seems it does only (maybe) effect the outcome of a game.