Eli Manning of the Giants looks on in the first half...

Eli Manning of the Giants looks on in the first half against the Cowboys at MetLife Stadium on Sunday, Dec. 10, 2017. Credit: Jim McIsaac

Old No. 10 deserved this. You bet he did.

It was unofficial Eli Manning Appreciation Day at MetLife Stadium, and the chilled fans greeted him with a standing ovation when he took the field against the Cowboys, then chanted his name when he threw a touchdown pass to put the Giants ahead.

All good, as far as it went. But then, inevitably, the Giants and their reinstated quarterback reverted to 2017 form, and what had been a tie game abruptly became a 30-10 loss.

Thus did the Giants fall to 2-11 on Sunday and move one step closer to selecting Manning’s potential successor early in next spring’s NFL Draft. Manning’s line: 31-for-46, 228 yards, one touchdown, two interceptions.

When interim coach Steve Spagnuolo was asked afterward to assess Manning, he instead veered off course and praised the play-calling of Mike Sullivan.

When asked if Manning will start against the Eagles next week, he gave a less-than-definitive endorsement:

“I don’t know. I’m not going to comment on that right now. That would be my gut feeling. But, look, without looking at it and evaluating it, Eli Manning is the quarterback right now.”

Then he added, barely audibly, “Unless something crazy happens.”

Let me help you out here, Spags, with nothing crazy required: Manning should start against the Eagles, but rookie Davis Webb should be active as the backup, and he should get into the game the minute things start going awry on offense.

Then, no matter what Manning does against Philadelphia, Webb should get his first start against the Cardinals in Arizona on Christmas Eve in a low-pressure environment free of cold, snow and ornery Giants fans.

Enough is enough.

Sure, the handling of Manning’s recent benching — or benching of himself, as you wish — was botched, and was no way for his 210-game starting streak to end. He deserved better.

But now he’s gotten it. That was what Sunday was all about. A victory would have been heartwarming, but the loss was the cold slap in the face everyone needed to get back to reality.

Coach Ben McAdoo and GM Jerry Reese are gone. Now it is Eli’s turn to step aside and allow everyone to get at least a taste of what young Webb can do before the season ends.

That does not mean Manning will not be back in 2018, although that seems increasingly unlikely. But what would be gained by having him play to the bitter end?

Manning said the right things when it was over, as he always does. He even praised the receivers who let him down with crucial drops. So let’s allow him to say a few words here before he runs out of downs and perhaps out of town.

“I appreciate all the support these fans have given me for 14 years, and these last weeks especially,” he said. “I appreciate them coming out and cheering me on, cheering the Giants on.”

He acknowledged support from friends, opponents and especially former teammates, some of whom showed up Sunday. Former receiver Plaxico Burress wore a No. 10 jersey. So did Victor Cruz.

“Those guys are about as loyal as it gets,” Manning said. “You don’t forget that. It reminds me to always be a great teammate. I feel like I’ve been a great teammate for 14 years and during the change [of starters], I was going to continue to be a great teammate.”

Manning said he did not think deep thoughts on the drive into work, only about winning. “Obviously these two weeks have been difficult with losing my starting job and losing your head coach,” he said.

“Those things are hard. They are unfortunate and hurt. I don’t like losing a head coach. I take that personally. That’s on me for not doing my job.

“I don’t like losing my starting job. That’s personal also . . . So I appreciate Spags giving me an opportunity to come in and get the start this week and see if we could get us a win. I’m sorry we didn’t play well enough to get that win.”

When safety Landon Collins was asked about the reception Manning received, he said, “Everybody loves Eli, that’s what it is. I love him, too.”

Nothing wrong with that. Nothing at all. Now give Davis Webb a jersey and let’s move forward.