If you watched the game, the Giants owned the time of possession, which means that the Panthers' defense stayed on the field longer, so they were worn out toward the end of the game after repeatedly pounding by RB Brandon Jacob. It explained the collapse of rushing defense later on.
Besides, their DT was out so their inside run defense was kinda vulnerable. The missing FG was mostly due to Giant stadium's notorious winter wind. It is hard to make a 50 yarder in that stadium In December and January