Many people on here especially the computer techno geeks will tell you it does not matter and that its a pre analysed result bla bla bla!, thats upto you to decide what you believe but me I personaly from my experience in the game think they do!, I have found that keeping your morale and condition above 90% for a match realy helps and reduces the chances of injuries!, also making substertution and rotating the squad works well to keep key player well rested.
Dont train till after you r last match of the day, use a full 22 man squad with two players in every position.