The Giants running back fans can’t wait to see leave the field

He runs in from the sideline and joins the huddle, accompanied by a sense of letdown from Giants supporters in the seats and watching on their sofas at home. The unrest is nothing personal, strictly business.

Saquon Barkley business.

Welcome to the football life of Wayne Gallman.

“It’s like, ‘Man, what am I doing wrong?’ ” Gallman told The Post this past week. “Like, my boy’s tired, I know I have to come in. It’s a fan base, it’s gonna happen, they’re gonna always want Saquon in there. They don’t want me in there.

“For the sake of the team and how our team is, I’m the second-string running back, and when he’s down or he’s tired, I have to be the one to go in. I was drafted last year. I’m a draftee. I would think it would be a little bit better, but it is what it is. I’m still gonna love the fans.

“I understand why they say it, there’s fantasy [football] and all this other stuff. When I’m on the field I can’t be thinking about, ‘Aw shoot, they don’t want me in here.’ I’m on the field thinking this play is gonna go for a touchdown or I’m gonna make this the most positive play I can.’’

Staying positive is a challenge. Gallman is an eager 24-year-old, and his Giants existence changed the instant Barkley arrived as the No. 2-overall pick in the 2018 draft. The year before, Gallman came aboard as a fourth-round pick from Clemson, a talented player with a sterling résumé. He set the school record with 1,527 rushing yards in 2015.

Gallman got 111 carries as a rookie and gained 476 yards, showing promise and improvement. There was every reason to project his role and workload would increase as he operated in tandem with the newcomer the Giants added to the offensive backfield.

But when that addition is “touched by the hand of God’’ — general manager Dave Gettleman’s description of Barkley — there is not going to be much sharing going on. Barkley through 12 games has 195 rushing attempts for 954 yards. Gallman has 29 carries for 103 yards. Barkley has 74 receptions. Gallman has 13.

“We draft Saquon, it’s another thing where, OK, he has a role for sure, as a No. 2 pick and from the business standpoint, I know exactly how it’s gonna go,’’ Gallman said. “I want to be out there as bad as he is, you know what I’m saying? Who doesn’t want to play, who doesn’t want to be great?

“At this time and place right now, where I’m at, I’m his backup and I’ve accepted it. I want the best for him. Of course in my head I want to be in his spot where he’s in now.’’

The Giants signed veteran running back Jonathan Stewart as a mentor and backup to get the tough yards, but it did not work out and Stewart is on injured reserve. It helps, Gallman said, that he and Barkley have “grown really close,” and Gallman views the burgeoning superstar as a kindred spirit as far as humble and hard-working traits.

“I’m ecstatic for my boy’s success,’’ Gallman said. “What he’s doing is incredible. Happy for him.’’

Barkley has hit every note just right, on and off the field, and his lack of any prima donna qualities turned what might have been an edgy relationship into a friendship.

“I believe that Wayne is a tremendous player,’’ Barkley said. “He runs hard. I have a lot of respect for Wayne, and as a competitor, he makes me get better every single day too, ’cause you know that you gotta bring it ’cause he’s a guy that when he gets on the field too, he’s gonna be able to make plays.”

At a position where timing is essential, Gallman never has the ability to acquire a feel for the game or the defense or even how his offensive line is blocking.

“There’s no rhythm,’’ acknowledged coach Pat Shurmur.

It is not helpful or reassuring to Gallman that when he is on the field and Barkley is not, it nearly triggers a federal investigation. Gallman took a series in the third quarter in Philadelphia, and his first two plays were gains of five and seven yards. A dropped pass and holding penalty short-circuited the possession, the Giants blew a lead, and it was as if Shurmur, based on the ensuing interrogation, had hidden Barkley in the Witness Protection Program.

“When he goes in there, people are critical of the fact Saquon’s not getting the touch,’’ Shurmur said, “but he’s being productive with his touches, and that’s important for a second back.’’

Gallman gets the ball and gains positive yardage, and the complaint is this: Saquon would have gained more.

“He’s done a good job,’’ Eli Manning said of Gallman. “He runs hard. He’s really done a good job getting positive runs, he lowers that shoulder, he gets that extra yardage. We don’t miss a beat once he’s in the game. Obviously his role is a little different, but he’s handled it well and prepared to go every week.’’

Gallman said he hears nothing but encouragement from fans during the game. Social media is another deal, where every snap Barkley misses is cause for outrage.

“I’ve seen a little bit of it, I don’t pay any attention to it, I don’t let it deter me,’’ Gallman said. “I understand it. Saquon has a huge fan base.’’

Shurmur inherited Gallman.

“My first exposure to him, in my mind he’s made huge improvements this year,” the coach said.

Most second-year backs do not have a Saquon Barkley in front of them.

“[Gallman] may not be a starter, but he would be a guy who would be more than a third,’’ Shurmur said.

Thoughtful and clear-headed, Gallman feels the vibe when Barkley runs for 50 yards and needs a quick rest.

“That’s when I come in for maybe one or two plays and ’Quan, I see him trying to get back in and I’m like, ‘All right.’ I wish I could finish, but it is what it is. It’s a business and I have to respect it. I’ve accepted it. That’s my boy ’Quan, and I’m OK with it.’’

There is no doubt Gallman can do more and also no chance Barkley will get less. This does not mean Gallman does not think about what he could do with Barkley’s touches.

“If someone’s offense turned their keys over to me, man, I would be ecstatic,’’ Gallman said. “I think I could be really good. My dream coming into the league and one of my goals in the back of my head is to be one of the best backs. I want to be remembered as one of the best backs. What back in the league doesn’t want that?’’

Barkley is on his way. Gallman mostly watches, and waits.