Obviously, another RB added to the roster before the Dallas game would have kept Lacy from being "run into the ground". Look at how many carries the 2 new RBs got in the Bears game. I believe that number was 4 or 5. This article talks about what happens when a player gets injured during a game and makes the injury report. http://www.nationalfootballpost.com/...ame-the-coach/
Condensing, it says he has to be cleared by the medical staff, team management has to be on board, and the player and his agent also have to agree that he's ready to play.
My recollection was that Starks didn't hIt the injury report until Tuesday or Wednesday of Dallas week. He had a personal issue that he had to take care of until Saturday when he had an MRI. He had surgery that evening or Sunday morning. The Packers implemented the Montgomery to RB during the week, and, I believe, would not have used Jackson much during the game had they activated him.
Lacy was cleared to play and aggravated his injury after carrying for almost 70 yds. Tough break, but I don't think it's on the GM.