I think it would really help gameplay if there was an option to place your second string in the game at the touch of a button. I think the human user should be able to place which ever player they want on the second-string, and, when they want to give first-string a rest and without having to spend five minutes hunting for the players that the user wants to put in the game, the pre-picked players that the user chose can be put into the game until the user de-selects them with the same button, much like how the defensive and offensive packages work, except with the entire offense and defense.