Cant substitute starting back! attributes dropping but can't keep him out!

OMG so annoying! I am winning a game by a good margin. I want to pull my starting back, since he is now showing high chance of injury, and all of this speed, agility and other attributes are tanked. It won't let me pull him! I have moved him to the very bottom of the depth chart, but he is still playing! You are going to get my starting back injured and screw my season! Here is the depth chart showing him at the bottom, yes still in the freaking game! I have tried just moving him to 3rd, but no matter where I put him, he continues to get in the game!!