Schwarber is not injured. He had some soreness at the beginning of the season that was ascribed to his not having as long a spring training. Plus, it made sense to have him DH and play Cave in LF anyway. Now, that was probably underplayed, but there is nothing going on with him that is not something you play through, especially if it's not affecting his performance (at the plate). If it hurt for him to swing the bat, different story. I know we also saw he was wearing a brace but not clear how long ago that was or if it's something he does all the time given his history of previous knee injuries. He was really bad last year too, it's just that this year he is worse and last year nobody cared because of A) his hitting and B) the 3B, 1B and RF appeared to be bigger defensive liabilities, though in fact they weren't really (and Hoskins was the best defender of the four of them, lol).
What I remember about Charlie's love of defensive replacements are the games where the bullpen blew it (not Lidge in 2008 obviously, but certainly other relievers, and all of them in 2009) and then Burrell's spot would come up in the order of a tie game. This was essentially the issue last night, given the likelihood that the Braves would score - albeit just one run ideally! - you needed Schwarber to still potentially come to the plate in the bottom of the 10th (and as it turns out, he did, and delivered, albeit fruitlessly by then).