For the first time in nearly three months, the leader of the Giants’ defense jumped into the huddle with the same boundless energy and enthusiasm as always. He was smiling and talking loudly, barking signals and encouragement.

Then his teammates looked up and asked “Who’s the new guy?”

The new guy, of course, was Jon Beason, the Giants’ irreplaceable middle linebacker, who practiced on Monday for the first time since June 12, when he tore a ligament in his foot and fractured a bone in his toe. His teammates were just having some fun at his expense. The truth is, they’ve been patiently waiting and hoping for his return all summer.

“He brings a presence that we’ve been missing,” said defensive tackle Cullen Jenkins. “He’s a leader, a natural leader, an intense person, and it’s great to have him back.”

“We need him,” added defensive end Jason Pierre-Paul. “Everybody knows we need him.”

There are other big parts to the Giants’ defense – a defense that defensive end Mathias Kiwanuka insisted is, when healthy, “one of the best defenses in the league”. Pierre-Paul’s health and ability to find his 2011 form is the key to the pass rush, and the Giants spent a lot of money upgrading their cornerbacks and safeties to build one of the best defensive backfields they’ve ever had.

But their most important offseason move came in mid-March when they brought Beason back with a three-year, $16.8 million deal. He transformed their defense last season when he arrived from Carolina in an early-October trade. He was an anchor during their struggles. He sorted through all their miscommunication. He was given tons of credit for turning them from a lost-looking unit into the NFL’s eighth-ranked defense.

And his teammates insist his importance hasn’t been overstated at all.

“He had a huge impact,” Jenkins said. “I think when times would get tough, he kind of took control of the defense. You had him to go to, to talk to, or whatever. He was going to keep things together. He was going to keep the communication going. It’s a presence that’s hard to teach.”

Every team that’s had any success has a leader or a “presence” like that. The Giants had it in Michael Strahan and Antonio Pierce in 2007, in Justin Tuck and Antrel Rolle in 2011. They were missing it last season during their 0-6 start, until Beason arrived in Week 4. And though things didn’t immediately improve, it didn’t take long. And the expectations were that this season he’d pick up exactly where he left off.

But as Beason pointed out on Monday, “You can’t lead if you are not in the fire with guys. How can I tell you what to do when I am over here hanging out, drinking Gatorade with a hat on?”

That’s why it was so disconcerting when he hurt his foot during a light spring practice. And it’s why it was so important to the Giants that he came off the Physically Unable to Perform (PUP) list and got back into the defensive huddle on Monday.

Because everything changes for the Giants’ defense when Beason is on the field, and it will mean everything to them if he’s able to play in Detroit on Monday night.

“I think that they trust that I am going to be there,” Beason said. “Obviously they are going to be smart. (But) by the end of the week, I think they will feel pretty confident that I can go out and contribute on whatever level they deem OK.”

Whether that’s a full or part-time role remains to be seen, but judging by how he looked on the field on Monday it’s hard to see him not playing at least a little on Opening Night. Beason said he felt “pretty good” taking what he said was a full workload at practice. But he also knows that the trainers are watching and so are the coaches.

Beason feels he still has something to prove.

“Obviously you want to gauge where I am mentally and physically,” he said. “What my role is going to be, how big or small, you don’t know. But I’m taking advantage of the reps they are giving me. I’m trying to prove why I need to be out there.”

There’s really no doubt about why he needs to be out there for the Giants. Tom Coughlin said that even “his presence on the practice field is going to change a lot of things.

“It’s the upbeat, the love to play, fly around a million miles per hour, encouraging other people to do the same or better, and just how hard he plays,” Coughlin said. “He shows great example in what he does.”

“I’m just glad he’s back out there,” Pierre-Paul added. “We were 0-6 (last year), and then we started winning when we had him at middle linebacker. You see it. That’s how you know we need him.”