Patrick Graham had his mind made up. He was going to Yale and choosing the undercover life of being a CIA agent. Two decades later, he can laugh at that early college aspiration that didn't work out. He's sure he made the right choice.

"If you go back and dig it up, there's film of it," Graham said. "But I found out early on when I got to school, chemical engineering wasn't for me and the CIA wasn't going to happen, either."

Graham is using his intelligence for football purposes, and though his new gig as Miami Dolphins defensive coordinator isn't covert like his former career path, he will demand that his players be extremely smart. His defense will be multiple, and it will require players to react, be versatile and spend extra time to learn responsibilities.

Preparation got Graham here, and he has made it clear that preparation will be essential for players to have a spot in the new Dolphins' defense.

Dolphins coach Brian Flores trusts Graham enough to hand him defensive playcalling duties. In this NFL era, first-time head coaches don't often give up that role on their side of expertise, and even fewer do so to a first-time coordinator. But Flores learned the importance of delegation from many of his mentors, including Falcons assistant general manager Scott Pioli, and he's confident that Graham has what it takes to excel in this role.

"Pat is a Yale guy. He's extremely bright. He is great with the fundamentals and has very strong leadership ability. I can't say enough good things about him," Flores said. "We worked together in New England and I know the type of passion he has and the way he works. We have a lot of the same core values and beliefs from a defensive standpoint."

Flores and Graham spent seven years together as Patriots assistants. They began their careers working as low-level staffers who shared an office. Graham said his most vivid memory from that time was the printer in that room, which brought a high volume of coaches coming in to get printouts.

Both have come a long way since those days -- Graham was the Packers' linebackers coach and run-game coordinator in 2018, when they tied for eighth in sacks and tied for 11th in fewest rushing yards allowed per carry -- but they valued going through the process because of the core principles it taught them. Now as Flores runs the Dolphins and Graham runs the defense, they know exactly what they want out of players.

"We want guys who are selfless, guys who are willing to work hard," Graham said. "Aside from the character traits, you want guys who play with their hands and are heavy-handed. You want guys to play with good knee bend and good leverage, and you want guys who have good eye discipline.

"In terms of the toughness, I want to have a way to measure the toughness. To me, you measure the toughness as a defensive player, and what we're going to talk about to those guys is, 'Can we stop the run, and can we stop the run when we know they're going to run the ball?'"

If run defense is a parameter for toughness, the Miami defense wasn't very tough last season. The unit finished 31st in that category, allowing more than 145 rushing yards per game. The Dolphins also ranked 29th in sacks, with just 31.

There's no easy fix for either category given Miami's roster setup. The Dolphins are headed toward a rebuild, and no group is more in need of an overhaul than the defensive line -- particularly the edge rushers.

Cameron Wake is a 37-year-old unrestricted free agent, and Robert Quinn led the Dolphins with 6.5 sacks, but he's set to make a tad under $13 million in 2019 and could be a salary-cap casualty. Veteran William Hayes is a free agent as well. The only other notable player set to be back in 2019 is Charles Harris, who has been a disappointment, totaling just three sacks since becoming Miami's 2017 first-round pick. Defensive tackle is a bit more promising with Davon Godchaux and Vincent Taylor as building blocks, but even with them that group couldn't stop the run in 2018.

The new scheme will affect the Dolphins' decisions. Miami has been a 4-3 team for years, but it will run more 3-4 formations under Flores and Graham. There are several misfits on all levels of the defense, but the new coaches seem prepared to undergo a rocky adjustment period as long as players bring a selfless approach to learning the new scheme.

"You better not have tunnel vision," said linebackers coach Rob Leonard, who has already identified the strengths of his top trio of linebackers: Jerome Baker, Kiko Alonso and Raekwon McMillan. "You better understand concepts from a schematic standpoint and see the big picture in what we're trying to accomplish, whatever we need to do to win a game. That's the ability, to be able to adjust."

Added Graham: "If it requires all 11 guys to be on their feet, it requires all 11 guys to be on their feet. If it requires all 11 to be down in a three-point stance, it'll look weird, but we'll do it if that's what we think is going to win the game."

He's joking, we think. But the Dolphins' defense will attempt to take on the manner of its coordinator: smart, hard-working, flexible and no tunnel vision.