John Mara’s unobstructed view from his box on the sixth floor of MetLife Stadium of the Giants being humiliated gave him a clear look at exactly what he and Steve Tisch must do at the end of the season. Fire GM Jerry Reese. Fire coach Ben McAdoo. Reese has run out of chances. McAdoo has lost the team and too many games. It’s time for a reboot and then let the new general manager and coach decide if they want to squeeze one transition year out of Eli Manning, who looked like a washed-up and broken down quarterback in the Giants’ 51-17 loss to the Rams, which unfortunately is how Manning has looked most of this season. Even with the Giants imploding week-by-week, McAdoo is either delusional or in a state or denial, because when I asked him if he was worried about his job, he said, “Not at all.” Mara is very much his father Wellington’s son, although John’s temper is legendary compared to his father’s calm demeanor. During lean years, Wellington used to say he could deal with the fans booing because that showed they still cared, but it’s when they didn’t show up for games that he needed to take action. Giants Nation sent a clear message to John Mara on Sunday: They are so disgusted they have lost interest. The Coaches Club seats, on the lower level directly behind the Giants bench, were maybe 30% filled. The mezzanine level from goal line to goal line on the Giants side of the field was virtually empty with fans scattered in small pockets. Those are the two most expensive areas of the stadium with the largest PSLs. Mara’s box is on the visitors’ side of the stadium down the hall from the press box. Of course, he saw the empty seats. They were right across from him.