Something different always happens when Justin Tuck stands at the center of the Giants’ pregame huddle.
It’s Giants tradition, this massive, emotional mosh pit in the end zone, just before the action gets started. The players gather around, and one of the team’s leaders takes over. Sometimes, Ahmad Bradshaw curses furiously. Other times, loudmouthed safety Antrel Rolle blathers on.

But when Tuck’s Alabama drawl commands the huddle, things are different. The Giants defensive captain says he’s never planned a speech, preferring to just “speak from the heart.” But it worked back on Feb. 5, when he spurred the Giants to the Lombardi Trophy. It works all the time, really.

“If Justin Tuck’s talking, everybody’s listening to him,” linebacker Spencer Paysinger says. “Everybody’s internalizing his speech.”

This Sunday afternoon, as the Giants get amped to face the Philadelphia Eagles in the finale of this regular season completely gone wrong, the Giants may internalize a Tuck speech for the last time.

The longtime leader of the Giants defense very well may leap into the middle of the final pregame mosh pit of his Giants career. An injury-ravaged Tuck has struggled to rush the passer this season, making just three sacks, his lowest total since 2006. And to a franchise that must fill serious defensive holes — and unsentimental GM Jerry Reese — Tuck may not be worth the $4.5 million that he’s due in 2013, the final year of his contract.

After eight years as a Giant, after playing a key role in two Super Bowl championship runs, Tuck could find himself cut after this nightmare season is over. And he knows it. A few years ago, he routinely scared opposing offenses; this year, his value has largely been tied to his ability to inspire his own defense.

“It could be (my last speech),” he says, sounding like a grizzled vet ready for the end. “I don’t allow myself to think about it. When it happens — and it will happen one day — I will move on.”

Frustration has been building for both player and management throughout this tumultuous 2012. He’s hardly the lone defender who has underperformed; sack artist Osi Umenyiora has just six QB takedowns, safety Kenny Phillips can’t even get on the field, and cornerback Corey Webster suddenly specializes in giving up long plays.

But Tuck’s decline has been the most precipitous. Much as he did last season, the 29-year-old has tried to gut out a series of injuries, looking to piece together one more late-season run.

This season, that run has not come. Beset by foot and shoulder issues, he hasn’t made a single play behind the line of scrimmage since Nov. 4. Defensive coordinator Perry Fewell has moved Tuck around, lining him up at defensive end, defensive tackle and even linebacker on rare occasions, but nothing has sparked a turnaround.

“Is he as effective as he was at the end of last year right now? No,” Fewell said. “Some days, he surprises me with what he does. And some days, it’s Justin.”

Tuck hasn’t been happy with his own play, either. Two weeks ago, the defensive end said bluntly that “I haven’t had a good year . . . Kiwi (Mathias Kiwanuka), Osi, none of us has had a good year compared to what we expect from ourselves.” His teammates have noticed a more sullen Tuck in the locker room, too.

“You can tell through his demeanor that he’s frustrated,” says defensive end Adrian Tracy, who occupies the locker next to Tuck at the Giants’ practice facility. “He’s not able to do what he’s capable of doing. Everybody knows what he’s capable of doing, and his body’s not allowing him to do it now.”

So the battered veteran has been left to do what he says he’s done since he was four years old, pushing his teammates a little bit harder. Giants linebacker Michael Boley can’t think of a single standout play from Tuck all season, but Boley says he’s inspired by watching him “persevere through a lot.”

And safety Stevie Brown recalls how Tuck pushed the Giants to shut down Robert Griffin III in the second half of a 17-16 loss in Washington on Dec. 3. After the Redskins scored 10 points against the Giants in the first half, Tuck “got the whole defense together” at halftime, Brown says, and exhorted them to “make plays.” Washington would score just one more touchdown in the second half.

“He’s still a presence on the team,” says Phillips. “He’s a leader. Whether it be getting a sack or giving a speech or just being out there, he means a lot to this organization.”

But somehow, the Giants will survive without Tuck, just as they thrived after Antonio Pierce was released in 2010. As Phillips says, the Giants have “more than one leader on this team.”

And as Tuck has realized this year, there’s far more to his life than the gridiron. He’s written a children’s book, and he continues to push for literacy. And on the Friday before the big game, his mind is far from football; he has to pick up his two-year-old son, Jayce.

“A lot of people get so wrapped up in the fact that I’m a football player,” he says. “I do so much more than football.”