Allen Park — If you’re wondering why he’s here, just look over there.

Long after the final whistle in practice — after the receivers have finished their final reps on the JUGS machine, after the coaches have left to prepare for meetings, after the equipment staff has taken their chores indoors — two Lions players remain on the practice field.

One is a rookie — defensive lineman Da’Shawn Hand — but the other is a 10th-year pro. And it’s no coincidence that when you ask Ricky Jean Francois why he’s still playing in the NFL, this is where he starts.

“All the extra stuff, it’s gonna show,” he says, wiping sweat from his brow as he finally makes his way to the locker room. “People are gonna see you work.”

You can tell he means it, too, and not just by the way he talks.

The 31-year-old Francois was signed to a one-year deal as a free agent just before the start of training camp. But he’s already working with the first-team defense in practice, lining up at tackle alongside Sylvester Williams.

And Francois, a 313-pounder with a solid track record as a run defender, is a big reason why more than a dozen defensive linemen are still out there past noon on another 85-degree day in mid-August, working on various techniques to shed blockers even after those blockers have shed their uniforms.

More: Lions focused on fixing sloppy run defense

More: Lions camp observations: Team reworks 2-minute drive

“I understand most people say, ‘Oh, he’s the teacher’ or whatever,” said Francois, who finished last season in New England playing for new Lions head coach Matt Patricia. “But I’m not, really. It’s just, ‘If you see me out here doing extra work, come along.’ It’s leading by example.

“It starts right here on the practice field, or in the film room, talking to coaches or taking notes. Somebody on the team is always looking at you. And if they do pick me, they’re looking at a person that wants to work, that wants to study, that wants to know the game.”

It’s a trait he says he picked up by watching others throughout his career — the 49ers’ Justin Smith, the Colts’ Robert Mathis and so on. And it’s one he’s not about to let slide now, considering how far it has gotten him, though he’s quick to add he’s not dragging any young players out there with him after practice.

“It’s gotta be within you to say, ‘OK, I see my vet out there doing it: Lemme see if I can learn a few things from him,’” he said. “I did it my whole career. … If you see a 10-year guy doing it, that should tell you something.”

And so should this, perhaps. That Hand, a fourth-round pick coming off an impressive preseason debut — one of the few bright spots defensively for the Lions in Oakland — was the last member of the position group still out there with Francois on Monday.

Asked later what the two were working on, Hand shrugged.

“Just technique, working on fundamentals — you can never forget the basics,” he said.

Besides, he added, “I’m young, I’ve got a lot to learn.”

What Francois has learned after all these years, though, is that the learning never ends. Detroit is his sixth stop in an NFL career that began as a seventh-round pick in San Francisco and has taken him to a pair of Super Bowls.

He began the 2017 season with Green Bay, but was cut loose by the Packers in November, signing with New England to add depth for an injury-depleted Patriots squad. Francois played three games, then was released again, but was re-signed in mid-December when starter Alan Branch went down because of a knee injury. He played well in a rotational role after that, even starting the AFC championship game against Jacksonville, and Francois apparently made a quick impression on Bill Belichick, who called him a “smart player” with “good instincts” and praised his work ethic back in January.

For Francois, though, the Super Bowl spot wasn’t the best part of last season.

“It was just me coming in and learning football all over again, and learning from that perspective,” he said. “The way Matt Patricia teaches it, the way Bill Belichick breaks it down, the way they give you everything about the game plan and over-prepare you, it was refreshing.”

Most refreshing, he says, was discovering the so-called “Patriot Way” really isn’t much more complicated than Belichick’s “Do Your Job” mantra that’s plastered on the walls in Foxborough — and now here in Allen Park as well.

“You just come in and you grind, you work your butt off, and you do your job — that’s it,” said Francois, whose other job, by the way, is as an owner of 30 Dunkin’ Donuts franchises from Savannah, Ga., to Miami, Fla. “That’s that’s the first thing I looked at every day when I walked in that building: Do your job. Don’t do nobody else’s job. Do your job.”

He did his job well enough to earn another shot in Detroit, where Patricia’s defensive remodeling has only just begun.

“You don’t have to be with a person a long time to build trust,” Francois said.

Now that he’s here, Francois is eager to build on that, diving into a playbook he could only skim last season. (“It’s just like when people tell you to read a book more than once,” he says, “because the second time you’re gonna pick up new stuff, or you may interpret it differently.”) He also shares a recommended reading list with teammates as a way of getting to know them better. (Paulo Coelho’s “The Alchemist” tops that list at the moment.)

But out here on the practice, he’s busy sharing what a decade in the NFL has taught him. The fundamentals are everything in this game, he says.

If you’re the example, everybody else is going to follow.