NFL

Latest MIA leaves Giants DOA

It is risky business to stamp R.I.P. on an NFL team’s gravestone, and certainly with seven games left, but if Chargers 21, Giants 20 was not the final nail in the coffin, there is no doubt that the hammering has begun in earnest.

Because Dead Team Walking has been exposed as team lacking toughness, a team lacking championship defense that can make the kind of championship stand that champions make, a team that has lost its killer instinct, a team that cannot be counted upon to defend Giants Stadium with all its heart and soul.

A team that does not respond to its head coach, Tom Coughlin, the way it has for much of the previous two seasons. A team that suffers from a disconnect with its rookie defensive coordinator, Bill Sheridan, and misses Steve Spagnuolo more than it will ever admit.

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Sheridan, turning off the pressure faucet, allowed Philip Rivers to effortlessly march the Chargers 80 yards in eight plays, the last one an 18-yard TD in the right corner of the end zone to Vincent Jackson past Corey Webster with 21 seconds left, and the air went out of Giants Stadium, and the 2009 season as well.

The boobirds — vultures, actually — savaged Dead Team Walking when it ended, and with good reason.

Call them frauds, call them flukes, call them imposters, call them pretenders, it’s all fair game.

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Antonio Pierce called this the Giants’ Super Bowl, and whatever Coughlin meant when he called this a one-game season, Dead Team Walking, loser of four straight, now heads into the bye week psychologically devastated.

This was the crossroads moment when the Giants vowed to throw away the clown outfits they had been wearing and show up with shoulder pads fueled by pride and anger.

Over the next 13 days, each and every one of them will be forced to look in the mirror and wonder whether their team has what it takes to be Lazarus.

Because the team that staggered out into the darkness last night simply is not good enough.

“When you hit bottom, that is when you see guys quitting,” Eli Manning said. “We didn’t quit.”

The Ray Handley Era aside, not quitting has never been the standard by which the modern-day Giants are judged.

Good teams finish. The rest of them wonder what might have been, and talk about not giving up.

“It’s not the end of the world,” Mathias Kiwanuka said. “We’re not gonna panic. We got seven more games left, seven chances to turn this around. It’s not over.”

Manning should have been the hero, because he was the one who answered the S.O.S. — Save Our Season — when he found TE Kevin Boss with the eight-yard TD pass in the left corner of the end zone that gave Dead Team Walking a 17-14 lead with just under nine minutes left.

Manning, given the sensible gameplan of orchestrating a short and intermediate passing game instead of the bombs-away against single coverage approach that had blown up in his face, looked unfazed, finally, by his right foot plantar fasciitis.

(Then again, why was Ahmad Bradshaw asked to get the third-and-2 and third-and-1 in the first half instead of Brandon Jacobs, 11-67?)

Big Blue had actually risen up in that fateful fourth quarter. And when Terrell Thomas intercepted Rivers and returned it 33 yards to the 4, it looked over.

Four yards to paydirt. Four yards to a reversal of fortune. Four yards to a statement victory.

And then Chris Snee, who faced the painful music, was flagged for holding Luis Castillo.

Manning to Hakeem Nicks short right, for no gain. Jacobs up the middle — the Chargers were in their dime package — for five yards.

No Manning. Jacobs up the middle for five more. Field goal.

“We gave them life,” Boss said.

So now it was life-and-death, Rivers at his 20 with 2:05 and one timeout left.

“There wasn’t any doubt that we were gonna close out the game,” Kiwanuka said.

Except you do not let Rivers (6-8, 75 yards) sit in his rocking chair on the last drive.

“Maybe there weren’t as many pressures,” Coughlin said. Pierce wasn’t around to talk about it. Osi Umenyiora sat shellshocked, chin on hand, at his locker.

“No one really gave us a shot at the bye our Super Bowl year, but we came back and found a way to get rolling,” Justin Tuck said.

That was then, this is now.

“You can write that the sky is falling, and then when we win a game, we’re back on track,” Shaun O’Hara said.

The sky has fallen.

steve.serby@nypost.com