With injuries, once on field a player is deemed fit. Now this is the hard part for players because depending on your status, ability and position some players still play suitable games which coaching staff assess is a risk worth takeing. Its never cut and dry, all players play hurt, believe me the medical room is busy game day. In 1986 I broke my right foot, but at first the exrays did not show it. badly bruised was the diagnosis,should be right in 2 to 3 weeks. well i couldnt get out of a jog, after 5 weeks i played in reserves, kicked 10, straight in seniors the next week, but foot was still very sore from playing, I played but struggled to run, doctors assured me thier was no bone damage so it must be me. This pattern continued all season till after struggling through 5 or 6 senior games they decided to get a cat scan, guess what the foot was fractured in 5 places. wasted a whole year. That was a major reason I left Melbourne. A coach says to a player. are you right to play, the player says yes ( because he doesnt want to let down the club, and the supporters!) He struggles , most coaches put it down to experiance and move on. If the player says no im not right, he gets called soft, or not tough enough to carry injuries. there would not be anyone who played the game at AFL level that has not been through it. Just remember what actually motivates footballers, they want more than anything to play and to play well. If they consistantly dont, apart from abilitiy, there is probably a physical cause. hope i havnt bored you cheers.