Manning, whose demotion set off a storm of criticism toward McAdoo and the Giants, offered support for his coach after the game.
“I don’t want that,” said Manning, whose streak of 210 consecutive regular-season starts came to an end. “I don’t want anybody to get fired. When a coach gets fired, it’s usually because the team and the players, and myself, haven’t performed to our duties. So I don’t want to see that. So I hope there’s no truth to it.”
McAdoo would not commit to using Smith again next week, when the Giants host the Dallas Cowboys, saying he and his coaching staff needed to examine the tape from an up-and-down performance against the Raiders. Smith, making just his second N.F.L. start since losing his full-time job with the Jets after the 2014 season, completed 21 of 34 passes for 212 yards and one touchdown.
But Smith lost two fumbles, including a critical red-zone turnover just before halftime. On a second-and-goal play from the Oakland 4-yard line, Khalil Mack sacked Smith and ripped the ball from his hands, denying the Giants a chance to tie the score or take the lead entering the half.
Instead, the Giants spent all day trailing and could not overtake the Raiders despite a pretty 10-yard scoring pass from Smith to tight end Evan Engram to cap an 88-yard drive with 5 minutes 22 seconds remaining in the game. The touchdown pulled the Giants to within 3 points, but Oakland responded with a 68-yard scoring drive of their own — highlighted by Cordarrelle Patterson’s 59-yard catch-and-sprint — to put the game away.
“I think as the game went along, we started getting into a groove,” Smith said. “We were able to kind of put some drives together late, but we just ran out of time.”
Smith had a moment of testiness during his postgame news conference, responding to criticism from the former Jets coach Rex Ryan, who said on ESPN, “I love Geno Smith. Great guy. I just don’t want him playing quarterback for me.”
Smith responded: “I did see one of my ex-coaches say he didn’t want me to be his quarterback, and that really upset me, you know?”
Smith went on to say of Ryan that “we saved his job in 2013” and “for him to come out and say that, just shows you how much of a coward he is.”
Manning was exemplary in his transition to the No. 2 role after authoring the second-longest starting streak for a quarterback in N.F.L. history. His first and only appearance on the field came during the captains’ meeting, when he came out for the pregame coin toss. He went from that familiar milieu to the unfamiliar task of clipping an audio pack to his waistband and putting in earphones as Smith’s backup. The rookie Davis Webb, a potential heir to Manning’s throne, was inactive.
Clusters of Giants fans came early to the stadium to pay their respects to Manning and express their displeasure toward the team’s management, chanting Manning’s name and holding signs emblazoned with slogans such as, “Big Blue Shame on You.”
“I understand where the fans are coming from,” McAdoo said. “If I was on the outside looking in, I’d feel the same way they feel. Eli and I have a tremendous relationship. I think the world of him. It was hard for me, emotionally at the beginning of the week, but once you made the decision, you have to stick with it, and I appreciate the way Eli handled it.”
Manning said after the game that he planned on playing in 2018. Whether it is for the Giants — and for McAdoo — remains to be seen.