ASHBURN, Va. -- After the initial meeting, a Saturday gathering to go over the first 15 plays the next day, ended, Bill Callahan kept his coaches at the Oakland Raiders facility. This was a time normally reserved for going home for a few hours. For Callahan, it became a time for more preparation.

They would spend hours doing more work: going over the game plan; discussing their plans on how to call the game; watching more film. It was classic Callahan, taking a detailed, meticulous approach.

It's an approach he has carried with him throughout his career, marked mostly by his offensive line teachings. And he'll take it into his new gig as the interim coach of the Washington Redskins.

One coach said sometimes those sessions lasted seven hours. But Redskins running backs coach Randy Jordan, who was on the Raiders staff in 2003, said that might be stretching it a little.

"Seven hours? Come on, you've got to go to sleep," Jordan said. "But he's detailed. I'll leave it at that."

But that attention to detail didn't lead to a head-coaching job in the past dozen years. This could be Callahan's last chance, at age 63, to prove he's worthy of a head-coaching job somewhere if that's what he wants.

As his first game approaches Sunday in Miami (1 p.m. ET, Fox), this is what you need to know about Callahan:

He's been a head coach twice

He took Oakland to the Super Bowl as a rookie head coach, losing to Tampa Bay. From there, it was downhill. After the Raiders posted an 11-5 mark his first season, they plummeted to 4-12 the next season, leading to him being fired. There was controversy -- receiver Tim Brown accused him of sabotaging the Super Bowl to help former Raiders coach Jon Gruden, who was then coaching the Buccaneers. It was a charge that Callahan flatly denied and that others rebutted.

In 2003, the Raiders were hit hard by injuries as quarterback Rich Gannon, the NFL MVP in 2002, played only seven games. One former player, who asked not to be named, said that Callahan relied on having veterans and that losing key ones ended up robbing the team of leadership. But Callahan didn't help himself by once referring to his Raiders as "the dumbest team in America."

The next season, he became the head coach at Nebraska, where he compiled a 27-22 record in four years before being fired.

"He's schematically intelligent," said former Redskins defensive lineman Adam Carriker, who played for Callahan at Nebraska. "He is very football-savvy. He operates a little differently. He's very business-oriented. He's to the next degree with that. But the personal relationship part and things of that nature maybe weren't his strong suit.

"The Raiders locker room wasn't happy with him before he came to Nebraska. There were cliques in the Nebraska locker room that weren't excited about him. As far as getting people to follow him, you want those coaches that you want to run through a brick wall for. Maybe those are areas that can be improved upon -- but he's probably grown and matured. I'll be curious to see how he approaches things now."

Since 2008, Callahan has been an assistant head coach and offensive line coach for the New York Jets, the Dallas Cowboys and the Redskins, whom he joined in 2015. Callahan said he's more patient than in his earlier coaching days.

"That just comes with age," he said. "You just learn how to become a better coach, a better communicator. That's one of the things I've learned through the course of time. You can just improve a player if you just try to find what it is he's all about. And then try to find that avenue to connect with him and create that relationship so they can be successful."

Jordan, a running back under him in 2002, said, "We were all different. He knows how to get the best out of you, but at the same time everyone accepts criticism differently. Part of being a good coach is you have to figure out how to tap into that."

He helped invent a new blocking sled

This past offseason, Callahan wanted to modernize blocking sleds to provide a more realistic drill for his players. He contacted Hans Krause, a longtime acquaintance at Rae Crowther Co., who designed a new sled with Callahan's input.

Callahan's goal was to mimic a defensive lineman's stance and leverage upon contact. The sled weighs about 320 pounds and contains shoulder pad chest plates, giving the linemen something to grab.

"The first time I did it, I said, 'This is the most realistic thing we're going to do,'" Redskins guard Brandon Scherff said. "[Callahan]'s always trying to ask you how you can improve it. It's perfect."

He likes to run the ball, but ...

He's not going to force it either. Callahan made it clear in his first two news conferences as the Redskins’ interim coach that he wants a stronger commitment to running. But it’s not as if his entire career has just been about running the ball. He is, after all, a former college quarterback (at the NAIA level).

With Callahan as the offensive coordinator in 2000, the Raiders led the NFL in rushing. Two years later, when he was the head coach, they led it in passing. But even in 2002, the Raiders had one game in which they rushed 60 times. In 2009, the Jets led the NFL in rushing under his direction. But the Redskins' run game has struggled.

In Callahan's two seasons as their coach, the Raiders threw more than they ran. But Callahan does want the Redskins to be more ground-and-pound.

"That run identity not only helps us be the physical team that we want to be but it lends itself benefits in every other area," Callahan said. "The defense, clock time ... . So we're really conscience of making that shift."

That, of course, was what Redskins running back Adrian Peterson wanted to hear. In four games, he has carried the ball 40 times for 108 yards.

"I'm hyped about it," Peterson said. "It's [been] totally opposite from what we did last year when we were able to be more successful as a team. Obviously something isn't working, so there needs to be some sort of change."

Did we mention he's detailed?

It's not just about having long meetings. Callahan has a reputation for being scientific in his approach and, for his linemen, that meant being exact with everything. They couldn't be off in their hand placement; they had to grab the shoulder pads of the defensive linemen a certain way on different blocks.

Redskins reserve center Tony Bergstrom said Callahan once told him of a certain technique he could use to counter a defensive lineman's hand placement.

"I tried it a couple times, and it worked every time," Bergstrom said. "I talked to him about it, and he says it always comes to him at 10 o'clock at night when he's watching film and watching some lineman somewhere else and he's probably doing something by mistake, and he's like, 'Oh, wow, that works. Let's try that.'"

Now that task is to turn those details into wins.

"It'll be interesting to see how it translates to our team as a whole," Bergstrom said. "As a line, we've loved working with him, so it's cool that the whole team gets to feel our pain."