Tom Pelissero

USA TODAY Sports

GLENDALE, Ariz. — Bruce Arians has been around football plenty long to know the perils of messing with roster dynamics.

“You don’t bring the wrong people into your locker room,” the Arizona Cardinals’ grizzled coach told USA TODAY Sports recently. “It only takes one.”

That probably says all you need to know about the Cardinals’ confidence that their two biggest, boldest acquisitions since January’s NFC title game flop will help them complete their ascent among the game’s elite, not send the whole thing sideways.

Robert Nkemdiche isn’t Randy Gregory. Chandler Jones definitely isn’t Greg Hardy. The Cardinals aren’t the Dallas Cowboys, who doubled down on gambles they've paid for since, with Hardy gone after one volatile season and Gregory among several key defenders suspended for drugs.

“You have to take some risks,” Cardinals general manager Steve Keim said. “Let’s be honest: Not every player out there that is extremely gifted has done everything right in his life. Yet at the same time, we want to create a culture in the locker room of positive guys, good people in the community.”

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Keim called that 49-15 loss to the Carolina Panthers to end last season the perfect storm.

“Not only did we play poorly, but all of our top players played poorly,” he said.

He also considered it a litmus test that showed some problem areas around the strong core driving the Cardinals’ 35-16 record and consecutive playoff appearances since this regime took over in 2013.

They needed a veteran leader for the offensive line, so they signed guard Evan Mathis, who just won a ring with the Denver Broncos. They needed to get longer and more athletic on the back end, so they signed safety Tyvon Branch and used a third-round draft pick on cornerback Brandon Williams, who both have shown well in camp. They needed to upgrade their front and, perhaps most important, improve their pass rush so they don’t have to blitz so much — skills for which NFL teams are paying a higher premium than ever.

If it weren’t for Jones’ shirtless, shoeless request for help at a police station in January, it may well have cost more than an injury-plagued guard and a second-round pick to pry him and his 36 career sacks from the New England Patriots, if he were available at all.

If it weren’t for Nkemdiche’s 15-foot fall from a hotel window in December, his top-10 talent — a souped-up version of former Cardinals standout defensive tackle Darnell Dockett — surely wouldn’t have been available with the 30th overall pick.

The Cardinals researched both men and the strange circumstances of the cases: Jones suffering a bad reaction to synthetic marijuana, according to The Boston Globe; Nkemdiche admittedly drunk and charged with misdemeanor marijuana possession after police found joints in the room.

“We feel like we got two high-character guys who made mistakes and know that they made a mistake and don’t feel like it’ll happen again,” Arians said.

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“Each person’s an individual. You look at Nkemdiche’s history and the family he comes from and everything. He had a bad night in Atlanta. And we all have bad nights. You don’t condemn them for that. You find out why, and what are you going to do about it? Chandler’s episode was bizarre — but he went to the police.”

Keim says he didn’t really believe in second chances until he saw the evolution of Tyrann Mathieu (aka the Honey Badger), who fell to the third round in 2013 after getting thrown off the LSU football team for drug issues but has developed into an all-pro defensive back and one of the Cardinals’ leaders.

Those second chances still are rare and calculated. Sign a time bomb like Hardy, an accused woman beater who did nothing on or off the field to rehab his image during the Cowboys’ injury-driven descent from 12-4 to 4-12, and pillars in the locker room such as quarterback Carson Palmer and receiver Larry Fitzgerald would be the first to say he needs to go.

“The inmates aren’t going to run the asylum here,” Keim said. “Because there’s enough of the Larrys, the Carsons, there are going to be certain actions or personalities that aren’t going to last here. The fact of the matter is we have an owner (former federal prosecutor Michael Bidwill, who chairs the NFL’s conduct committee), a head coach and a general manager who aren’t going to put up with it, either.”

There’s little question Jones and Nkemdiche can be difference makers for a team that was one bad day away from the Super Bowl last season. And both have drawn positive reviews before they’ve played a down.

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“We don’t judge people,” said Mathieu, who was recently rewarded with a five-year, $62.5 million contract extension. “We all come from different backgrounds. We’ve all got stuff in our closets. So, it makes no sense for us to judge people. We kind of accept anybody and everybody.

“Our biggest concern as players is, are those players committed to playing football?”

Keim has built this roster by taking chances, more on the field than off, whether it’s small-school studs (e.g. David Johnson), talented athletes who aren’t polished in position play (Deone Bucannon) or aging veterans many consider declining or done (Palmer in a 2013 trade, Chris Johnson and Dwight Freeney off the street during camp last year).

Giving one-year extensions to Palmer, 36, and Fitzgerald, 32, was a sign the Cardinals are focused on sustaining their rise, not taking one last shot. And while Jones’ future is uncertain — he’s in a contract year and figures to strike it rich if he produces — adding him and Nkemdiche doesn’t convey the desperation of the Cowboys’ attempts to get over the top in 2015.

“You get aggravated that you hear people on the radio or whoever it may be asking me questions: ‘Wow, you’re really going for it, huh?’” Keim said.

“I’m going for it every year! Our head coach and my mentality is put your foot on the gas pedal and don’t let off.”

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