Hard to play your best people when you have already clinched a spot and home field advantage. Ask most players what they would rather have,,,Super Bowl or a perfect season. If I'm the coach I will let my quarterback play only to keep him sharp and game ready but would not let him play the whole game because all it takes is one play to take him out. Ask Joe Theismann about that. It's always a good idea to give the backup quarter some playing time anyway and a good coach will find ways to get some playing time for them during the regular season. Practice is not the same as a real game and that is why successful teams will play their back ups just like they do in basketball. If you can't go deep into your bench you are only one play away from disaster IMHO.